Adhesive bonding composition and method of use

ABSTRACT

A method of and system for adhesive bonding by a) providing a polymerizable adhesive composition on a surface of an element to be bonded to form an assembly; b) irradiating the assembly with radiation at a first wavelength capable of vulcanization of bonds in the polymerizable adhesive composition by activation of sulfur-containing compound with at least one selected from x-ray, e-beam, visible, or infrared light to thereby generate ultraviolet light in the polymerizable adhesive composition; and c) adhesively joining two or more components together by way of the polymerizable adhesive composition.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.15/322,928, filed Dec. 29, 2016, now allowed, which is a 371 of PCTapplication no. PCT/US15/38290, filed Jun. 29, 2015, which claimsbenefit of priority to U.S. provisional application No. 62/018,915,filed Jun. 30, 2014, the entire contents of each of which are herebyincorporated by reference. The present application is related to U.S.application Ser. No. 15/126,834, filed Sep. 16, 2016, now U.S. Pat. No.10,087,343, which is a 371 of PCT application no. PCT/US15/21307, filedMar. 17, 2015, the entire contents of each of which are incorporatedherein by reference. The present application is also related to U.S.Provisional application Ser. No. 61/955,547, filed Mar. 19, 2014, theentire contents of which is hereby incorporated by reference. Thepresent application is also related to U.S. Provisional application Ser.No. 61/955,131, filed Mar. 18, 2014, the entire contents of which ishereby incorporated by reference. The present application is related toU.S. Provisional application Ser. No. 61/331,990, filed May 6, 2010, andU.S. Provisional application Ser. No. 61/443,019, filed Feb. 15, 2011,the entire contents of each of which are hereby incorporated byreference. The present application is also related to U.S. provisionalpatent application 61/161,328, filed Mar. 18, 2009; U.S. provisionalpatent application 61/259,940, filed Nov. 10, 2009; U.S. ProvisionalApplication Ser. No. 60/954,263, filed Aug. 6, 2007, and 61/030,437,filed Feb. 21, 2008; U.S. application Ser. No. 12/059,484, filed Mar.31, 2008; U.S. application Ser. No. 11/935,655, filed Nov. 6, 2007; U.S.Provisional Application Ser. No. 61/042,561, filed Apr. 4, 2008;61/035,559, filed Mar. 11, 2008; and 61/080,140, filed Jul. 11, 2008;U.S. patent application Ser. No. 12/401,478 filed Mar. 10, 2009; U.S.patent application Ser. No. 11/935,655, filed Nov. 6, 2007; U.S. patentapplication Ser. No. 12/059,484, filed Mar. 31, 2008; U.S. patentapplication Ser. No. 12/389,946, filed Feb. 20, 2009; and U.S. patentapplication Ser. No. 12/417,779, filed Apr. 3, 2009, the entire contentsof each of which is hereby incorporated by reference. This applicationis related to U.S. patent application Ser. No. 13/102,277 filed May 6,2011, the entire contents of which is hereby incorporated by reference.This application is related to U.S. patent application 61/735,754 filedDec. 11, 2012, the entire contents of which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION Field of Invention

The invention pertains to materials and methods for polymer curing,particularly adhesive curing and bonding, and more particularly tomethods for using energy conversion and photoinitiator chemistries inapplications where access to an external light source is not available.

Discussion of the Background

Thermosetting polymers and adhesives are well known and are used for awide variety of applications. One particularly important applicationdomain is in the field of microelectronics assembly, where thermosetadhesives are used to bond bare die to substrate, establish conductivecontacts, and perform various roles in packaging and sealing structuressuch as glob-top and die-underfill structures. Commercially availablematerials are formulated to meet various requirements, and in additionto the monomer(s) may contain particulate fillers such as metal, oxides,or dielectric powders, as well as various additives to control thermalconductivity, viscosity and other properties. The materials aretypically dispensed as a thixotropic fluid in precise locations, andafter all the parts are placed, the entire assembly is heated to atemperature necessary to polymerize the monomers or crosslink resins.

As modern electronic components evolve to smaller sizes, and integratedcircuits include ever-smaller features such as ultra-shallow junctions,the permissible thermal budget during assembly continues to decrease.New memory device technologies, for example, incorporate phase-changematerials that are temperature sensitive and may need to be assembledusing low-temperature processing. Similarly, polymer composites used fordental restorations must be cured without subjecting the patient to highcuring temperatures. To address these issues, many photo-curing polymersystems have been developed. In general, these systems employ at leastone photoinitiator, which, when exposed to UV light, releases chemicalenergy to form free radicals or cations to initiate the reaction of themonomers at substantially ambient temperatures.

The clear limitation of conventional photoinitiators is the need to havedirect line-of-sight access to a suitable light source. This preventsthe use of conventional materials for advanced processes such asmultilayer stacks of individual silicon dies, because there is no way toget the UV light into the interior of the stack.

Furthermore, the conventional UV curable adhesives cure from the outsidesurface of an adhesive bead to the inside of the adhesive bead; and, inmost cases curing is accompanied by the formation of a skin. In thepresent invention curing is more controllable and can proceed across theentire volume of the adhesive bead.

SUMMARY OF THE INVENTION

One object of the present invention is to provide polymer formulations(i.e. monomers, photoinitiators, adhesion promoters, and energyconverters) that can be activated (and subsequently cured) by indirectphotoinitiation, i.e. in the absence of line-of-sight access to theexternal energy source.

A further object of the present invention is to provide adhesivecompositions that may be cured at ambient temperature and that readilyadhere across the interface between the photoactivatable resin and thesubstrate or medium being adhered to.

Another object of the present invention is to provide an adhesionpromoter or an adhesive promoting treatment to increase the strength ofthe resultant bonded complex.

Another object of the present invention is to provide an adhesionpromoter or an adhesive promoting treatment to increase the strength ofthe resultant bonded complex when adhered to a low surface energysubstrate.

Another object of the present invention is to provide a flexible sheetadhesive material capable of being polymerized by selected ionizingradiation.

These and other objects and advantages of the invention, either alone orin combinations thereof, have been satisfied by a method of and systemfor adhesive bonding that comprises the steps of:

a) treating a surface of an element to be bonded to provide an adherentstructure including one or more rubber compounds on said surface;

b) placing a polymerizable adhesive composition, including at least onephotoinitiator and at least one energy converting material, in contactwith the adherent structure and two or more components to be bonded toform an assembly;

c) irradiating the assembly with radiation at a first wavelength,capable of conversion by the at least one energy converting material,preferably a down converting material such as a phosphor, to a secondwavelength capable of activating the at least one photoinitiator toproduce from the polymerizable adhesive composition a cured adhesivecomposition; and

d) adhesively joining the two or more components by way of the adherentstructure and the cured adhesive composition.

These and other objects and advantages of the invention, either alone orin combinations thereof, have been satisfied by a curable polymer systemcomprising an adherent structure attached to a low energy surface of anelement to be bonded (the surface having a surface energy less than 50mJ/m²), at least one polymerizable adhesive composition for adhesiveattachment to the adherent structure, at least one photoinitiatorresponsive to a selected wavelength of light, and at least one energyconverting material selected to emit the wavelength of light whenexposed to an imparted radiation.

These and other objects and advantages of the invention, either alone orin combinations thereof, have been satisfied by an adhesive transfermember comprising a release substrate, one or more rubber compoundsdisposed on a surface of the release element, and an energy convertingmaterial intermixed the one or rubber compounds in the a surface of therelease element.

BRIEF DESCRIPTION OF THE FIGURES

Various other objects, features and attendant advantages of the presentinvention will be more fully appreciated as the same becomes betterunderstood from the following detailed description when considered inconnection with the accompanying drawings in which like referencecharacters designate like or corresponding parts throughout the severalviews and wherein:

FIG. 1A is a schematic depicting two substrates bonded together usingthe methods and systems of the present invention.

FIG. 1B is a schematic depicting a textile bonded to a substrate usingthe methods and systems of the present invention.

FIG. 1C is a schematic depicting an adhesive transfer sheet for transferof natural or synthetic rubber compounds onto a substrate to be bonded.

FIG. 1D is a schematic depicting the bonding of two substrates togetherusing rubber compounds of the present invention.

FIG. 2A provides an emission spectrum of a material that emits in theUVB regime, upon irradiation with X-rays.

FIG. 2B provides an emission spectrum of a material that emits in theUVB regime, upon irradiation with X-rays.

FIG. 3 provides an emission spectrum of a material that emits in theUVA, UVB, and visible regimes, upon irradiation with X-rays.

FIG. 4 provides emission spectra of two separate materials, CaWO₄ andYaTO₄, upon irradiation with X-rays.

FIG. 5 provides an emission spectrum of a mixture of CaWO₄ and YaTO₄,upon irradiation with X-rays.

FIG. 6 provides emission spectra of a mixture of CaWO₄ and YaTO₄, uponirradiation with X-rays at intensities of 50, 90, and 130 kvp.

FIG. 7 provides a representation of the effects of a large coatingthickness or coating shape on packing factor of a phosphor.

FIG. 8 provides the changes in attenuation of intensity of X-ray betweena phosphor that has a coating and an innate phosphor surface.

FIG. 9 provides a representation of an embodiment of a dam-and-fillapplication of the present invention.

FIG. 10 provides a representation of an embodiment of the presentinvention using an insertion molded piece placed in the substrate tointensify the UV output.

FIGS. 11A and 11B show a representation of a bare silica carrierparticle and a silica carrier particle decorated with nano-size phosphorparticles, respectively.

FIG. 12 provides a representation of a silica carrier particle coatedwith quantum dots or alloyed quantum dots or metal alloys exhibitingplasmonic behavior under X-ray.

FIG. 13 provides a representation of a silica carrier particle decoratedwith nano-sized downconverters and then coated with silica.

FIG. 14 provides a representation of a photoinitiator tethered oradsorbed on the surface of a nano-sized phosphor particle.

FIGS. 15A and 15B provide representations of a silica micro particledecorated with nano-size phosphor particles having photoinitiatorstethered or adsorbed on the surfaces thereof and photoinitiatorstethered directly on a silica coating around a particle that isdecorated with nano-sized phosphors, respectively.

FIGS. 16A and 16B provide representations of a double layered decorationthat is non-tethered with photoinitiators and a double layereddecoration with tethered photoinitiators, respectively.

FIG. 17 provides a representation of one suitable chemistry fortethering inorganic down converter particles to the photoinitiator.

DETAILED DESCRIPTION OF THE INVENTION

In one embodiment of this invention, a class of curable adhesives isutilized by the present invention in combination with an adhesionpromoter or an adhesion promoting treatment. This class of adhesives hasone or more of the following desirable attributes:

-   -   a—Cure without line of sight (bond line where the adhesion takes        place is internal to structures to be bonded)    -   b—Cure without depth of penetration limitation (Bond line can be        deep inside materials without compromising the cure kinetics)    -   c—Cure without thermal expansion mismatch (ability to bond at        room temp and to avoid compressive and tensile stresses at the        bond line)    -   d—Cure adhesive selectively (only where the adhesive has an        energy converting particle does the adhesive form a network;        this can be used to generate selective curing geometries)    -   e—The adhesives have suitable properties (electrical—including        dielectric non-conductive to anisotropically semiconductive to        conductive, mechanical—rigidity or compliancy (use of a second        phase flexibilizer), optical—from transparent to opaque, Acid        vs. Base Control—ability to withstand a variety of environments        from Inks to aqueous solutions, Adhesive Bond strength of a        desirable range)

These attributes make it possible to improve on existing adhesive curingapplications. The present invention's adhesive curing and bonding leadsto novel assemblies and processing methods that are advantageous ascompared to the state of the art.

In one embodiment, the present invention provides a way to bondmaterials at ambient temperature using photoinitiator chemistries thatconvert absorbed light energy (typically UV light) to chemical energy inthe form of initiating species such as free radicals or cations andthereby initiate a polymerization reaction in a monomer-containingadhesive. In another aspect, the invention provides a way to performphoto-initiation in situations where the area to be bonded is notaccessible to an external light source.

According to one embodiment of the invention, the adhesive compositioncomprises: an organic vehicle comprising at least one polymerizablemonomer; at least one photo-initiator responsive to a selectedwavelength of light; and, at least one energy converting materialselected to emit the selected wavelength of light when exposed to aselected imparted radiation.

One issue associated with the bonding of two substrates together isthat, while the photo initiated curing can partially or completely curethe polymerizable adhesive composition, the adhesions of those materialsto the respective substrates being bonded together requires additionalselection of structures or materials which have the capacity to bond toeither substrate.

According one embodiment of the invention, the method of adhesivebonding comprises the steps of: a) treating a surface of an element tobe bonded to provide an adherent structure on said surface; b) placing apolymerizable adhesive composition, including at least onephotoinitiator and at least one energy converting material, in contactwith the adherent structure and two or more components to be bonded toform an assembly; c) irradiating the assembly with radiation at a firstwavelength, capable of conversion by the at least one energy convertingmaterial, preferably a down converting material such as a phosphor, to asecond wavelength capable of activating the at least one photoinitiatorto produce from the polymerizable adhesive composition a cured adhesivecomposition; and d) adhesively joining the and two or more components byway of the adherent structure and the cured adhesive composition.

In one embodiment, the adhesive composition includes curable polymersystem comprising an adherent structure attached to a low energy surfaceof an element to be bonded (the surface having a surface energy lessthan 50 mJ/m²), at least one polymerizable adhesive composition foradhesive attachment to the adherent structure, at least onephotoinitiator responsive to a selected wavelength of light, and atleast one energy converting material selected to emit the wavelength oflight when exposed to an imparted radiation.

In one embodiment, the adhesive composition includes an adhesivetransfer member comprising a release substrate, one or more rubbercompounds disposed on a surface of the release element, and an energyconverting material intermixed said one or rubber compounds in the asurface of the release element.

The methods and systems described herein as part of the invention, thesemethods and systems permit the at least one energy converting materialto be either a downconverting material, and upconverting material or acombination of thereof. In one aspect of the invention, thedownconverting material can comprise inorganic particulates selectedfrom the group consisting of: metal oxides; metal sulfides; doped metaloxides; and mixed metal chalcogenides. In one aspect of the invention,the downconverting material can comprise at least one of Y₂O₃, Y₂O₂S,NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃, LaF₃, LaCl₃, La₂O₃, TiO₂, LuPO₄, YVO₄,YbF₃, YF₃, Na-doped YbF₃, ZnS; ZnSe; MgS; CaS and alkali lead silicateincluding compositions of SiO₂, B₂O₃, Na₂O, K₂O, PbO, MgO, or Ag, andcombinations or alloys or layers thereof. In one aspect of theinvention, the downconverting material can include a dopant including atleast one of Er, Eu, Yb, Tm, Nd, Mn Tb, Ce, Y, U, Pr, La, Gd and otherrare-earth species or a combination thereof. The dopant can be includedat a concentration of 0.01%-50% by mol concentration.

In one aspect of the invention, the downconverting material can comprisematerials such as ZnSeS:Cu, Ag, Ce, Tb; CaS:Ce, Sm; La₂O₂S:Tb; Y₂O₂S:Tb;Gd₂O₂S:Pr, Ce, F; LaPO₄. In other aspects of the invention, thedownconverting material can comprise phosphors such as ZnS:Ag andZnS:Cu, Pb. In other aspects of the invention, the downconvertingmaterial can be alloys of the ZnSeS family doped with other metas. Forexample, suitable materials include ZnSe_(x)S_(y):Cu, Ag, Ce, Tb, wherethe following x, y values and intermediate values are acceptable: x:y;respectively 0:1; 0.1:0.9; 0.2:0.8; 0.3:0.7; 0.4:0.6; 0.5:0.5; 0.6:0.4;0.7:0.3; 0.8:0.2; 0.9:0.1; and 1.0:0.0.

In other aspects of the invention, the downconverting material can bematerials such as sodium yttrium fluoride (NaYF₄), lanthanum fluoride(LaF₃), lanthanum oxysulfide (La₂O₂S), yttrium oxysulfide (Y₂O₂S),yttrium fluoride (YF₃), yttrium gallate, yttrium aluminum garnet (YAG),gadolinium fluoride (GdF₃), barium yttrium fluoride (BaYF₅, BaY₂F₈),gadolinium oxysulfide (Gd₂O₂S), calcium tungstate (CaWO₄), yttriumoxide:terbium (Yt₂O₃Tb), gadolinium oxysulphide:europium (Gd₂O₂S:Eu),lanthanum oxysulphide:europium (La₂O₂S:Eu), and gadoliniumoxysulphide:promethium, cerium, fluorine (Gd₂O₂S:Pr,Ce,F), YPO₄:Nd,LaPO₄:Pr, (Ca,Mg)SO₄:Pb, YBO₃:Pr, Y₂SiO₅:Pr, Y₂Si₂O₇:Pr,SrLi₂SiO₄:Pr,Na, and CaLi₂SiO₄:Pr.

In these methods and systems, the wavelength of radiation capable ofconversion by the at least one energy converting material can be atleast one of X-rays, electron beams, deep UV light (e.g., 160-400 nm fordown conversion). In these methods and systems, the wavelength ofradiation capable of conversion by the at least one energy convertingmaterial can be near infrared (e.g., for up conversion).

In these methods and systems, down converting and/or upconvertingmaterials (such as those described herein) can be included in an organicvehicle which is cured by activation of a photoinitiator containedtherein or by vulcanization of a sulfur containing compound therein.

In these methods and systems, the organic vehicle (e.g., a polymerizableadhesive composition) can comprise a monomer forming a thermoset resin.The thermoset resin can be selected from the group consisting of:acrylics, phenolics, urethanes, epoxies, styrenes, and silicones. Inthese methods and systems, the at least one photoinitiator can beselected from the group consisting of: benzoin ethers, benzil ketals,α-dialkoxyacetophenones, α-aminoalkylphenones, acylphosphine oxides,benzophenones/amines, thioxanthones/amines, and titanocenes. In thesemethods and systems, the polymerizable adhesive composition furthercomprises inorganic particulates selected from the group consisting of:metals and metal alloys, ceramics and dielectrics, and metal-coatedpolymers. The polymerizable adhesive composition can further comprise anorganic component selected from the group consisting of: solvents,viscosity modifiers, surfactants, dispersants, and plasticizers.

In these methods and systems, the adherent structure can be provided byway of a solution containing natural or synthetic rubber (i.e.,rubber-like) compounds which are disposed on the surface of an elementto be bonded, the solvent can be removed (e.g., by evaporation), and therubber compounds can be polymerized.

Natural Rubber, Isoprene and Poly-Isoprene:

Natural rubber has a long fatigue life and high strength even withoutreinforcing fillers. It can be used to approximately 100° C., andsometimes above. It can maintain flexibility down to −60° C. ifcompounded for the purpose. It has suitable creep and stress relaxationresistance and is low cost.

Furthermore, natural rubber as utilized in various embodiments of thisinvention includes milled grades of the natural rubber. Natural rubberas shown above can be a naturally-occurring polyisoprene elastomerrecovered from the sap of rubber trees (Hevea brasiliensis) and certainother trees and plants. Natural rubber as a commodity can generally besupplied in solid form or as alkali-stabilized latex.

In one embodiment of this invention, the “rubber-like” compounds caninclude isoprene. Isoprene can be derived from many plants. Isoprene, or2-methyl-1,3-butadiene, is a common organic compound used across a widerange of industrial applications and can be found with the followingformula CH₂═C(CH₃)CH═CH₂. Isoprene has the advantage of being acolorless volatile liquid and therefore can be blended with variousother compounds that are compatible with its miscibilitycharacteristics.

An example of polyisoprene is shown below, where a poly cis-1,4 isopreneis shown as the building block of a longer chain.

Once the longer chain is crosslinked, the crosslinked material developselastomeric properties. The elongation of the material depends on thenumber of crosslinks that are imparted to form the network. When under atensile stress, the networked material can stretched. When the stress isremoved, the material fully recovers (as long as it has been stressedbelow its non elastic deformation threshold).

For solvent-based adhesives or primers utilized in various embodimentsof this invention, the solid natural rubber is usually masticated on atwo-roll mill prior to being dissolved in hydrocarbon solvents. Althoughit is possible to prepare solutions of unmilled natural rubber, millingreduces gels, thereby affecting viscosity, stability, uniformity andspeed of dissolving. Solvents such as toluene can and have been used todissolve the natural rubber compounds into a mixture that which can beapplied to the surfaces of substrate a and substrate b.

Natural rubber can be utilized in various embodiments of this inventionwhere its bonds are cross-linked by the assistance of ultraviolet lightgenerated from at least one or more of down converting or up convertingmaterials (such as the ones described above). The natural rubberformulations in the present invention (prior to inclusion of energymodulation agents) then follows, for example, conventional formulationsand preparations such as those described in “UV-curable natural rubberssuch as those described in “Ultraviolet curing of acrylated liquidnatural rubber for surface coating application,” Songklanakarin J. Sci.Technol. 31 (1), 49-55, January-February 2009, the entire contents ofwhich are incorporated herein by reference.

Accordingly, in one aspect of the present invention, ultraviolet lightgenerated from at least one or more of down converting or up convertingmaterials (such as the ones described above) can be used to cross-linkthe following liquid natural rubber (LNR) samples:

-   -   1) The liquid natural rubber (LNR) obtained by degradation of        20% DRC natural rubber latex with hydrogen peroxide of 0.5 phr        and cobalt acetylacetonate of 1 phr by means of mechanical        stirrer in a round bottom flask at 65° C. for 72 hrs. LNR was        precipitated in methanol and then dried in a hot oven at 40° C.    -   2) Epoxidized liquid natural rubber (ELNR) obtained from 10% w/v        LNR in toluene. Formic acid and hydrogen peroxide in ratio of        30:60 (mol % with respect to isoprene unit) added drop wise and        stirred at 50° C. for 2 hrs. ELNR was then washed in 5.0% NaHCO3        solution, precipitated in methanol and dried at 40° C.

In one aspect of the present invention, ultraviolet light generated fromat least one or more of down converting or up converting materials (suchas the ones described above) cross links a rubber prepared from theliquid natural rubber compounds noted above, and/or other liquid naturalrubber compounds. For example, the ultraviolet light generated from atleast one or more of down converting or up converting materials (such asthe ones described above) can serve to cross link a surface coatingmaterial obtained by the mixing of LNR with 80 phr tripropylene glycoldiacrylate and 10 phr Irgacure 651.

Moreover, it has been discovered that natural and synthetic rubbercompounds can be directly activated by x-ray flux to bond and be used asthe interface material between the respective substrates and the curedpolymers. Such natural and synthetic rubber compounds can be prepared ina fine powder form, applied to the surfaces, and then exposed to x-rayenergy for example energy at 320 kVp, 160 kVp or 106 kVp. Higher orlower kVp energies can be used in various embodiments of the invention.X-ray energies ranging up to 1-10 MeV can be envisioned if necessary.However, lower x-ray energies are preferred, both from an exposurestandpoint, and from the standpoint of avoiding detrimental effects asside reactions to the high energy x-rays. In one embodiment of theinvention, MVp energies are used to penetrate more deeply into theobject being cured. In one embodiment of the invention, 10-100 kVpenergies are used where the object being cured is on a surface of anarticle or relatively close to the surface or inside of a low massnumber material such as a plastic. In general, the selection of the kVpwill depend on a number of factors including the geometry andconstruction of the material being cured, the x-ray dose, and the rateof production desired.

In one embodiment of the invention, the rubber-containing bondingcompounds (upon being exposed to this x-ray flux) have shown thecapacity to bond to the low energy substrates. Energy modulation agentssuch as the down converters and upconverter described herein are notnecessarily needed. In one embodiment of the invention, once theserubber compounds have been bonded to the respective substrates, then oneof the photo initiated curing processes described below can be used toform a robust adhesion of substrates through the primer interface andthe intermediate cured polymer resin between the substrates. In oneembodiment of the invention, these rubber compounds bonded to therespective substrates can be directly bonded together withoutnecessarily using the intermediate cured polymer resin between thesubstrates.

Accordingly, the natural rubber compounds provide a double-bond backbonewhich can be activated by x-ray alone or either by UV light generated byx-ray phosphors (discussed below) which emit UV light upon exposure tox-rays or an e-beam flux. When using down converters the UV light isused to specifically open a double bond in the natural rubbers.

Accordingly, in the methods and systems of this invention, thepolymerization of disposed rubber compounds on the surface of theelement to be bonded can be accomplished by exposing the rubbercompounds to at least one of x-rays, e-beam, or UV flux. While not tiedto any particular theory, the exposing can break or “open up” doublebonds in the rubber compounds, followed in turn by bonding of the rubbercompounds to the surface of the element to be bonded. With thisapproach, the solution is provided with a concentration of the naturalor synthetic rubber compounds between 33% and 45%. Other concentrationsare also possible.

With regard to e-bean activation, electrons of an energy range of 80-300keV, for example, can break chemical bonds and generate ions. The ionsthen transform themselves into free radicals, which then initiatepolymerization. Electron beams having an energy of 80-300 keV capable ofcuring even pigmented resins of about 400 μm as well as clear coatingsof up to 500 μm stability for the cured coatings. The present inventionis not limited to this range of e-beam energies. Other (in particular)higher energy e-beams can be used. Prior rubber compound vulcanizationstudies have reported the use of e-beam induced vulcanization fromelectrons out of a 1.8 MeV accelerator with an output power of 10.8 kW.

The paper entitled “Comparison between electron-beam and chemicalcrosslinking of silicone rubber” in Nuclear Instruments and Methods inPhysics Research B 243 (206) 354-358, the entire contents of which areincorporated herein by reference, describes silicone rubber compoundsbeing irradiated by electron beams in the absence of chemical reagents.The silicone rubber compounds described therein are useful in variousembodiments of this invention where x-rays, e-beam, or UV flux (from forexample the down converters or up converters described herein) initiatechemical crosslinking without necessarily the need to add chemicalreagents to promote the crosslinking.

The following is a list of rubber compounds suitable for the presentinvention. (The present invention is not limited to this list.) The listincludes four kinds of rubber samples: NR (natural rubber), EPDM(ethylene-propylene terpolymer) rubber, EVA (ethylene vinyl acetate)rubber and CPE (chlorinated polyethylene).

NR Rubber:

NR+0 phr TMPT, containing 62.70% NR and 37.30% filler;

NR+3 phr TMPT, containing 61.52% NR, 1.85% TMPT and 36.63% filler;

NR+6 phr TMPT, containing 60.42% NR, 3.63% TMPT and 35.95% filler;

NR+9 phr TMPT, containing 59.35% NR, 5.34% TMPT and 35.31% filler.

EPDM Rubber:

EPDM+0 phr TMPT, containing 62.70% EPDM and 37.30% filler;

EPDM+3 phr TMPT, containing 61.52% EPDM, 1.85% TMPT and 36.63% filler;

EPDM+6 phr TMPT, containing 60.42% EPDM, 3.63% TMPT and 35.95% filler;

EPDM+9 phr TMPT, containing 59.35% EPDM, 5.34% TMPT and 35.31% filler.

EPDM+12 phr TMPT, containing 58.31% EPDM, 7.00% TMPT and 34.69% filler.

EVA Rubber:

EVA+0 phr TAC, containing 62.70% EVA and 37.30% filler;

EVA+3 phr TAC, containing 61.52% EVA, 1.85% TAC and 36.63% filler;

EVA+6 phr TAC, containing 60.42% EVA, 3.63% TAC and 35.95% filler;

EVA+9 phr TAC, containing 59.35% EVA, 5.34% TAC and 35.31% filler.

CPE Rubber:

CPE+0 phr TAC, containing 62.70% CPE and 37.30% filler;

CPE+3 phr TAC, containing 61.52% CPE, 1.85% TAC and 36.63% filler;

CPE+6 phr TAC, containing 60.42% CPE, 3.63% TAC and 35.95% filler;

CPE+9 phr TAC, containing 59.35% CPE, 5.34% TAC and 35.31% filler.

In one embodiment of the present invention, blended rubber compoundssuch as for example acrylonitrile butadiene rubber-poly vinyl chloride(NBR-PVC) blends can be exposed to e-beams to affect a cure. Energymodulation agents such as the down converters and upconverter describedherein can be included but are not necessarily needed. Dose rates from25 to 150 kGy are effective in curing these blends.

Blends of acrylonitrile butadiene rubber (NBR) and poly vinyl chloride(PVC), with a density of 0.7-1.2 g/cm³, are commercially available.Acrylonitrile butadiene rubber-poly vinyl chloride (NBR-PVC) is amiscible physical mixture of commercial importance. The NBR can act as apermanent plasticizer for PVC. The presence of PVC improves agingresistance of NBR as both PVC and NBR are polar and blending NBR withPVC increases the compatibility. The aim in blending plastic and rubberis to improve the physical, thermal, and mechanical properties as wellas to modify the processing characteristics and cost reduction of thefinal product.

Crosslinking and Vulcanization:

The formation of a network in a “rubbery” material can be done usingvarious methods. When dealing with a “rubbery” material, the most commonway of forming a network between chains is called vulcanization.

Vulcanization of rubber is well known and can be generally defined asthe formation of crosslinks between the polymeric chains using sulfur,heat, curing agents, accelerators and other sensitizing chemistries.

Sulfur Cross Linking

Vulcanization is an example of cross-linking. The schematic above is anillustration of two “polymer chains” (a lower chain and an upper chain)cross-linked after the vulcanization of natural rubber with sulfur (n=0,1, 2, 3 . . . ).

Alternatively, the crosslinks between rubber chains can be achievedusing peroxides, UV light, electron beam, microwave, etc. The use ofperoxides as crosslinking agents is well known and offers the potentialto carry out the crosslinking process at lower temperatures. In fact alllow temperature process alternatives have the potential of reducingdegradation by oxidation and limit rubber blooming when compared to thestandard sulfur based vulcanization. However, the properties developedwith standard vulcanization are considered superior to those developedwith alternate methods. Commercial products such as ethylene-propylenerubber (EPM), fluoro-elastomers (FKM) can undergo peroxide cure toundergo crosslinks formation between chains and result in the formationof a stable network with good properties. This crosslinking is done viathe covalent carbon-carbon bonds. Both unsaturated and saturatedpolymers can be processed using peroxide curing methods. The mechanicalproperties and thermal stability that are obtained are directly relatedto the number of crosslinking taking place in the network. Highercrosslink density would result in more stable rubbery compounds.

In the present invention, peroxide curable rubbers were achieved usingactivation through a down conversion from X-Ray energy to UV light usingphosphor materials (and other energy modulation agents both downconversion and up conversion described herein). One of the advantages ofthe present invention is that the rubbers can be activated with nodirect line of site. This allows the rubber doped with peroxidegenerators and the phosphors to remain un-reactive until such a timethat X-Ray activation is performed. Incidentally, the same phosphors canconvert energy from an Electron Beam (EB) to UV energy suitable forperoxide activation and initiation of the curing. A further advantage ofthis method is the low energies required to carry out the curing. TheX-Ray energy/dose and the e-beam energy/dose used for activation can berange from 20 mGy to 3 Gy as opposed to standard EB ionization that canrequire up to 10 kGy.

In one embodiment of the present invention, the natural and syntheticrubber compounds and/or the blends noted above are applied to surfaceand then vulcanized to form a cured product bonded to the substrate.Vulcanization may be considered to have occurred when two radicalsproduced on neighboring polymer units recombine. These radicals canproduced by a chemical agent, such as peroxide or sulfur. In general,vulcanization is a process for converting rubber or related polymersinto more durable materials via the addition of sulfur or otherequivalent curatives or accelerators. These additives modify the polymerby forming crosslinks (or bridges) between individual polymer chains (asshown above). Vulcanized materials are typically less sticky and havesuperior mechanical properties. In one embodiment of the presentinvention, radiation, such as electron beam or gamma radiation can beused to cause vulcanization of polymers. These and other vulcanizationtechniques can be used in the present invention. As used herein,vulcanization is the process of converting natural or synthetic rubbersfrom their natural state into a more robust durable state where thenatural or synthetic rubbers are cross linked.

In one embodiment of the present invention, the interaction of electronbeam radiation with a polymer results in the formation of free radicalsby dissociation of the excited state or by ion molecular reaction. Thevulcanization reaction occurs during the irradiation of the polymer.Coagents, such as ethylene glycol dimethacrylate (EDMA), trimethylolpropane trimethacrylate (TMPTMA), or trim ethyl-propane trimethacrylate(TPTA) can be used to reduce the dose required for cross-linking.

In one embodiment of the present invention, the natural and syntheticrubber compounds and/or the blends noted above can also be activated byUV light emitted for example from a downconverter converting x-rays (ore-beams) into UV light to cure or otherwise vulcanize the natural andsynthetic rubber compounds and/or the blends noted above. In oneembodiment of the present invention, the natural and synthetic rubbercompounds and/or the blends noted above can also be activated by visiblelight emitted for example from a downconverter converting x-ray ore-beams into visible light or for example from an upconverter convertinginfrared light into visible light to cure or otherwise vulcanize thenatural and synthetic rubber compounds and/or the blends noted above.

One of the most common agents used for vulcanization is sulfur. Sulfur,by itself, is a slow vulcanizing agent and does not vulcanize syntheticpolyolefins. Even with natural rubber, large amounts of sulfur, as wellas high temperatures and long heating periods are necessary.Vulcanization accelerators are used including activators like zinc oxideand stearic acid. The accelerators and activators are catalysts. Anadditional level of control is achieved by retarding agents that inhibitvulcanization until some optimal time or temperature.

In one embodiment of the present invention, vulcanization is achieved bythe activation of sulfur-containing compounds added to the polymerizableadhesive compositions. The sulfur-containing compounds can themselves byphosphors and can be activated by UV light or directly by x-ray orelectron beam exposure. While not bound to a particular theory, uponactivation (i.e., exposure to UV light or direct exposure to x-rays orelectron beams or other high energy particles), free radicals aregenerated which serve to cross link the natural or synthetic rubbercompounds.

More specifically, in one embodiment of this invention, a lowtemperature sulfur based crosslinking occurs. In this particular case,natural rubber is mixed with a media that undergoes a partialdegradation under X-Ray to release a substantial level of sulfur. Oncethe sulfur is released between the polyisoprene chains, it can be madeto react further in the presence of X-Ray or EB energy. In the case thechemical reaction can be carried out under thermal heat or not. Highertemperatures were found to accelerate the curing. However, even in thepresence of room temperature, the curing is enhanced when X-Ray of EBenergy is supplied to the material undergoing the reaction. Thechemistries employed can remain partially cured for days and acceleratedtoward full cure by X-Ray energy when needed. This is advantageous froma manufacturing stand point since production line stoppage can takeplace and work in process can be maintained in a queue until such timethat X-Ray or EB energy is applied to the materials.

This aspect of the present invention reduces the amount of energyrequired to obtain X-Ray and/or EB curing. This is very useful in viewof the fact that radiation curing has limited adoption in themanufacturing environment due to the high level of energies required anddue to the high cost of radiation equipment capable of delivering highlevels of energy. By reducing the energy level required, the presentinvention can be utilized in more industrial applications thanpreviously considered possible.

X-Ray Curable Rubber Containing Sulfur Chemistry:

The compounded rubbers in the present invention included in one example,Cake Rubber (that has undergone a mastication process consisting ofshear through a milling machine), a Tackifying resin (C5 & C9 resins), aWood Rosin (turpine based short chain), Kraton (a synthetic polymer) andXylene (a solvent). These components were mixed and prepared to form arubber base. The prepared rubber based was then used to form a curablerubber. The curable rubber in this case was formed by adding IronSulfate hydrated 10:1 in water to the rubber base. Eight grams of therubber base was used to which 0.25 grams of the hydrated Iron Sulfatewas added, followed by the addition of 0.25 grams of IRGACURE 250 (whichcontains an iodonium salt). See attached BASF data sheet. Furthermore,one gram of a sulfur containing phosphor was added. Phosphors such asCaS phosphor and/or ZnSeS are suitable. The mixture was then stirred andallowed to homogenize.

0.5 grams was applied to a silicone treated Mylar film to cover asurface area of 1 in by 4 in. The rubber mixture was then flattened tohave a thickness of about 1 mm. The Mylar containing this rubber patternwas allowed to dry in air or under 60° C. heat. The solvent was removedin less than 10 minutes, and the rubber coupon on the Mylar firm wasdried. At this stage the rubber coupon is very tacky but malleable.

The Mylar film was removed from the hot plate. The rubber coupon wasaligned with a low energy substrate. The rubber coupon and the lowenergy substrate were pressed together to make intimate contact. TheMylar film was then removed from the rubber coupon and then rubbercoupon was therefore left in contact and on top of the low energysubstrate. The low energy substrate was unprimed and yet the tackinessof the rubber coupon was good enough to provide enough mechanicalinterlocking to hold the substrates in contact. Another substrate wasthen placed on top of the rubber coupons to form a sandwich where therubber coupon was maintained under pressure.

The assembly formed by the two substrates sandwiching the rubber couponwas then exposed to X-Ray energy. A total of five such assemblies wereexposed to X-Ray energy, and a total of three such assemblies wereprepared but not exposed to X-Ray energy. The X-Ray energy exposureconsist of 180 sec under energy produced using 320 kVp, 10 mA in aPrecision X-Ray machine. The assemblies were then tested for peelstrength.

This was done by splitting one end of the assembly apart. About half aninch (0.5 in) was slices apart at the join line where the rubber couponis located. One end of the low energy substrate was attached to a fixlocation while the end of the second substrate was attached to a fivepound weight. In this configuration the rubber coupon was subjected topeel (which is a known test in the industry). The three assemblies thatwere not processed under X-Ray were also tested for peel. The elapsedtime for the five pound weight to peel the three and half in length ofthe bonded assembly was then measure. The faster the time to rip throughthe joint the weaker is the rubber coupon. The longer it takes theweight to fall the more crosslinks have formed and the more indicationof curing has taken place. The average time for the five pound weight tofall for the three assemblies that were not processed under X-Ray was 2seconds. The average time for the five pound weight to fall for the fiveassemblies that were processed under X-Ray was three and half minutes.This indicated that crosslinking is taking place.

X-Ray Curable Rubber Containing Sulfur Chemistry as Well as Peroxide:

Another category forming a rubber base chemistry was prepared using themixture described above as well as the inclusion of additional agents toaccelerate the cure and was found to be effective in networking therubber coupon forming the joint. In this case, a chain transfer agent(mercaptopopinate) was added. Also, the rubber base included atrifunctional monomer. Also, the addition of cobalt-acetate orcopper-naphthenate promotes the kinetics.

In this case, the cure can proceed with the sulfur-vulcanization as wellas a peroxide based curing. Assemblies have a peel time of close to fiveminutes were made which indicate that the formation of crosslink of therubber.

Multifunctional monomers (MFM) can be added to enhance the propertiesvarious chemistries can be used. MFM are more important in the case ofthe peroxide curable rubbers. Multi-functional agents which can be addedto the mixture are organic molecules with a high reactivity to freeradicals. A tri-functional monomer as part of the rubber mix for eitherthe peroxide cure or for an addition to the Natural Rubber cured withsulfur under X-Ray.

In one embodiment of this invention, multifunctional co-agents such asdescribed in Chapter 1 of “Aspects Regarding Radiation Crosslinking ofElastomers,” by Manaila et al, are suitable for the present invention.The “Aspects Regarding Radiation Crosslinking of Elastomers,” article isattached, and the contents of which are incorporated herein by referencein entirety. Multifunctional co-agents can be classified in two groups:Type I and Type II co-agents.

Type I:

Addition and hydrogen abstraction reactions: these co-agents consist ofrather polar molecules with a low molecular weight and activated doublebonds. Their main characteristic is that they are highly reactivetowards radicals, so scorch takes place very fast, which sometimes canbe a disadvantage. By using this kind of coagents not only the rate ofcure is increased but also the crosslink density or state of cure. Adisadvantage that may be present when using this type of co-agents isthat, due to polarity, the compatibility of these co-agents with thepolymer matrix is limited. Some examples of Type I co-agents are:acrylates, methacrylates, bismaleimides and zinc salts.

Type II:

Addition reactions: these co-agents are, in general, less polarmolecules, which form more stable free radicals. The use of theseco-agents leads to an increase in crosslink density but unlike Type I,Type II co-agents do not typically increase the cure rate. Due to theirlow polarity, Type II co-agents have a good compatibility with manyelastomers. Some examples are: high-vinyl 1,2-polybutadiene,divinylbenzene, allyl esters of cyanurates, isocyanurates and sulphur.

One liquid rubber compound that successfully cured using peroxidechemistry was Hypro 1300 X43 VTBN—liquid rubber (methacrylate terminatedbutadiene-acrylonitrile). Two chemistries were prepared as follows. Thefirst chemistry was prepared with Hypro 1300 80%, Dipropylene glycoldiacrylate 14%; 6% TPO (thermoplastic polyolefin). The second chemistrywas prepared using the following mixture of Hypro 1300 80%,Pentaerythritol tetraacrylate (PETA) 14%; 6% TPO. To both of thesechemistries were added a LaOBr Phosphor for activating peroxide basedcuring. These chemistries were effective in curing various high energysubstrates; however, these chemistries were not as compatible with thelow energy substrates and therefore did not wet the surface as well asthe other examples evaluated.

Additional agents can be added to accelerate the cure. An example ofsuch accelerator is QDO (Quinone Dioxime) from Lord Corporation. QDO isa non-sulfur vulcanizing agent that can be added to synthetic elastomersto accelerate the curing kinetics.

The Formation of Adherent Structures:

FIG. 1A shows two substrates where an adherent structure has been formedon the surfaces thereof. A variety of adherent structures are describedelsewhere, but for the purpose of illustration, the adherent structurein FIG. 1A can be considered by way of an example to be the cured orvulcanized natural and synthetic rubber compounds and/or the blendsnoted above. Once the adherent structure has been formed, thepolymerizable adhesive compositions noted above and described in moredetail in other sections of this specification can be applied in betweenthe substrates, the substrates pressed together, and the polymerizableadhesive composition cured to form the structure in the lower half ofFIG. 1A.

In these methods and systems, the surface of the element to be bondedcan comprise a low energy material having a surface energy of less than50 mJ/m², less than 40 mJ/m², or less than 30 mJ/m².

In these methods and systems, the surface of the element to be bonded(and optionally the interior) can comprise at least one of apolytetrafluoroethylene, a poly(perfluoroalkylacrylate), a polystyrene,a polyacrylate, a poly(methyl methacrylate), a poly(dimethylsiloxane), apolyethylene, a polychlorotrifluoroethylene, a polypropylene, apolyvinyl chloride, a polyvinyl fluoride, a polyvinylidenedichloride, apolyvinylidenedifluoride, a polyacrylamide, a polyethyleneterephthalate, a poly(6-aminocoproicacid), and apoly(11-aminoundecaroicacid). In these methods and systems, the surfaceof the element to be bonded (and optionally the interior) can compriseat least one of a silicone and a poly (dimethyl siloxane).

In one embodiment of this invention, besides priming the substrates asdescribed above, other processes can be used such as a plasma etch (forexample an air plasma which would be cost effective) and or a chemicaletch to form the adherent structures noted above. Accordingly, invarious methods and systems of this invention, the adherent structurecan be formed onto or into the surface of the element to be bonded bymodifying the surface of the element to increase a surface energythereof. In these methods and systems, the adherent structure can beformed onto or into the surface of the element to be bonded by exposingthe surface to a plasma treatment. The plasma treatment can be atreduced pressures or at or above atmospheric pressure conditions. Inthese methods and systems, the adherent structure can be formed onto orinto the surface of the element to be bonded by exposing the surface toa chemical etchant.

In these various methods and systems, the adherent structure can beformed onto or into the surface of the element to be bonded by applyinga primer to said surface of the element to be bonded. The primer cancomprise a two-component urethane-based primer. The two-componenturethane-based primer can be a moisture activated primer.

One issue associated with the use of inorganic phosphors is that thesephosphors tend to be fairly large in dimension on the order of microns.In one embodiment of the invention, luminescing organic pigments areused as though organic phosphors described above. These situations ofthe organic phosphors are much smaller in size than the inorganicphosphors noted above. Accordingly, such phosphors can be integrallymixed into the polymerizable adhesive composition or into therubber-containing bonding compounds. This organic or “molecular” type ofphosphor then allows for the concentration of phosphor in the curing andbonding layers to be minimized relative to that which will be necessaryfor the larger organic size phosphors. Accordingly the cross linkingbetween the phosphors will generate a more robust and complete chemicalbond between substrates.

In the various methods and systems of this invention, the at least oneenergy converting material can be an organic phosphor. The at least onephotoinitiator is configured to be activated by emitted light from oneor more of organic phosphors. The organic phosphor can be at least oneof anthracene, sulfoflavine, fluorescein, eosin, polyvinyltoluene,styrene, fluors, and rhodamine. The organic phosphor is linked to the atleast one photoinitiator.

In one embodiment of this invention, primers (as noted above) can beapplied to those substances (for example the commercially availableprimer known as from ATPRIME® from Reichhold) which involves a two partprimer part A and part B. The present invention has found this primer tobe particularly advantageous for the bonding together of dissimilarsubstrates. Any convention primer can be used as desired. Preferredprimers that can be used in the present invention include, but are notlimited to, silane/silanol functional materials, polymeric isocyanates,energy curable polymers, solvent based epoxy functional, solvent basedsynthetic rubber, ethyl acetates, chlorinated polymers, hydroxylterminated polymers, isocyanate terminated oligomers, amine functionalpolymers, metal titanates, phosphate and phosphonate esters, metalsalts, and combinations thereof.

In one embodiment of the invention fluorescent organic molecules can beattached to different reaction sites and serve as the photo initiators.In one embodiment, these fluorescent organic molecules can be rolledinto a polymer chain. The polymer chain can support side groupattachments or chain terminations and can be a part of a networkincluding the fluorescent organic molecules and the polymerizableadhesive compositions.

In one embodiment of this invention, the substrate can be considered atextile or a fabric. The fabric can then include a set of fibers thatincludes the fluorescent molecules woven into a thread of the textile.The interweaving or threading of the fluorescent organic moleculesthrough the textile allows for activation of the polymerizable adhesivecomposition disposed at the interface between the textile. Theinfiltration of polymerizable adhesive composition into the intersticesof the textile itself promoted the bonding and adherence the textile tothe opposing substrate.

FIG. 1B is a schematic depicting a textile bonded to a substrate by wayof UV fibers in the textile activating a polymerizable adhesivecomposition which had previously been supplied. As shown in FIG. 1B,adherent structures on the surface of the substrate can be used ifneeded.

In the present invention, the energy converting material can be anymaterial that can convert the imparted energy either into higher energyphotons (“upconverting material”) or into lower energy photons(“downconverting material”). Suitable upconverting materials anddownconverting materials are described in U.S. provisional patentapplication 61/161,328, filed Mar. 18, 2009; U.S. provisional patentapplication 61/259,940, filed Nov. 10, 2009; U.S. ProvisionalApplication Ser. No. 60/954,263, filed Aug. 6, 2007, and 61/030,437,filed Feb. 21, 2008; U.S. application Ser. No. 12/059,484, filed Mar.31, 2008; U.S. application Ser. No. 11/935,655, filed Nov. 6, 2007; U.S.Provisional Application Ser. No. 61/042,561, filed Apr. 4, 2008;61/035,559, filed Mar. 11, 2008; and 61/080,140, filed Jul. 11, 2008;U.S. patent application Ser. No. 12/401,478 filed Mar. 10, 2009; U.S.patent application Ser. No. 11/935,655, filed Nov. 6, 2007; U.S. patentapplication Ser. No. 12/059,484, filed Mar. 31, 2008; U.S. patentapplication Ser. No. 12/389,946, filed Feb. 20, 2009; and U.S. patentapplication Ser. No. 12/417,779, filed Apr. 3, 2009, the entiredisclosures of each of which are hereby incorporated by reference. Theimparted energy can be any desired energy as needed to penetrate thematerial between the imparted energy source and the adhesive compositionitself. For example, the imparted energy can be near-infrared (NIR),with an upconverting material to convert the imparted energy into UVphotons that can be absorbed by the photoinitiator used. Preferably, theimparted energy is X-ray energy, with the energy converting materialbeing a downconverting material, such as a phosphor or scintillator. Forconvenience, the following discussion will refer to downconvertingmaterials and the use of X-rays as the imparted energy. However, this isnot intended to be limiting of the present invention and any desiredcombination of imparted energy and energy converting material can beused, so long as the photons generated by the energy converting materialare capable of being absorbed by the photoinitiator.

In an associated method, without limitation: the polymerizable adhesivecomposition can be dispensed in a selected pattern through a needle orscreen printing, or otherwise through a mask having a selected pattern;or otherwise through photo-patterning; or otherwise through pre-formingthe adhesive composition into a sheet (optionally with isotropic oranisotropic conductivity). Pressure can be applied to the polymerizableadhesive composition if necessary to assist in the bonding.

The dispensing of the polymerizable adhesive compositions and theadhesive properties thereof can be adjusted to meet any one or more ofthe following:

-   -   The dispensing can be performed using any conventional        dispensing system, including, but not limited to, dispensing        using piston or auger pumps, spin coating, spray coating, or        screen printing.    -   The adhesive can contain a tracer element for inspection, if        desired.    -   The adhesive can contain a pigment for optical inspection, if        desired.    -   The adhesive can be made to change color after curing, if        desired.

In one embodiment of this invention, an adhesive transfer sheet can beused to transfer the above-noted natural or synthetic rubber compoundsonto a substrate to be bonded. FIG. 1C is a schematic depicting anadhesive transfer sheet for transfer of natural or synthetic rubbercompounds onto a substrate to be bonded. With this approach, a sheetmade of mylar (for example) is pulled through a solution of theabove-noted natural or synthetic rubber compounds in which various downconverters and/or up converters are also in suspension.

The rubber compounds and the down and/or up converters transfer to themylar sheet forming a continuous or quasi-continuous coating thereof. Inthis approach, the coated sheet is now able to be cut or otherwiseshaped to fit prescribed regions where two or more substrates such asthe low energy substrates (noted elsewhere) are to be bonded together.Once applied to one of the substrates, the adhesive transfer sheet ispressed and the rubber compounds with the down and/or up converters aretransferred to the first substrate, and the mylar sheet removed. Thistransfer process can conform or otherwise dispose the rubber compounds(with the down and/or up converters) to a surface of the firstsubstrate. In some embodiments, the down and/or up converters may beomitted if the vulcanization of the rubber compound is to occur bydirect x-ray inducement or other high energy particle bombardment, suchas electron beam induced curing of the rubber compounds.

Subsequently, a second substrate (or more substrates) can be pressedinto contact with the transferred rubber compounds (with the down and/orup converters), and thereafter upon x-ray or other appropriateactivation energy the rubber compounds can be used to cure or otherwisevulcanize the rubber compounds, thus binding the substrates together.

FIG. 1D is a schematic depicting the bonding of two substrates togetherusing rubber compounds of the present invention.

Thus, in one embodiment of this invention, there is provided an adhesivetransfer member including a release substrate, one or more rubbercompounds disposed on a surface of the release element, and an energyconverting material intermixed said one or rubber compounds in the asurface of the release element. The adhesive transfer member can includedownconverting or upcoming material (such as those described above orbelow). The downconverting material can include inorganic particulatesselected from the group consisting of: metal oxides; metal sulfides;doped metal oxides; and mixed metal chalcogenides. The downconvertingmaterial can include at least one of Y₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG,YAP, Nd₂O₃, LaF₃, LaCl₃, La₂O₃, TiO₂, LuPO₄, YVO₄, YbF₃, YF₃, Na-dopedYbF₃, ZnS; ZnSe; MgS; CaS and alkali lead silicate includingcompositions of SiO₂, B₂O₃, Na₂O, K₂O, PbO, MgO, or Ag, and combinationsor alloys or layers thereof. The downconverting material can include adopant including at least one of Er, Eu, Yb, Tm, Nd, Mn Tb, Ce, Y, U,Pr, La, Gd and other rare-earth species or a combination thereof. Thedopant can include at a concentration of 0.01%-50% by mol concentration.A preferred embodiment uses a combination of Y2O3:Gd+LaOBr:Tm phosphorsor Y2O3:Gd+LaOBr:Tb phosphors. The upconverting material can include atleast one of Y₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃, LaF₃, LaCl₃,La₂O₃, TiO₂, LuPO₄, YVO₄, YbF₃, YF₃, Na-doped YbF₃, or SiO₂ or alloys orlayers thereof.

Bonding of Materials:

The present invention permits the bonding of composites to othercomposites (especially to low energy surface materials), to metals andmetal alloys, to rubbers, to leather and to inorganic materials (such asceramics), particularly useful in bonding of non-like materials to oneanother. In one embodiment, the bonding to the low energy surfacematerials in turn permits the polymerizable adhesive compositionsincluding the adherent surface structures to in turn be bonded tovariety of other materials including those described above and below.

Attaching Mechanical Fasteners to Composites:

The present invention permits the bonding of small metallic componentsto large composite panels such as rivets which can be useful to fastentwo separate structures. Conventionally, this requires the use of metalon metal contact to accomplish a welded connection. The presentinvention's polymerizable adhesive compositions including the adherentsurface structures permit a much wider manufacturing freedom ofoperation. For aerospace and automotive applications, for example, aKUKA robot (sold by KUKA Aktiengesellschaft of Augsburg, Germany) can beequipped with an adhesive applicator (such as a dispenser) and an X-raysource as well as a pick and place machine to: dispense the adhesive,perform optical inspection, place a rivet and hold it in place, and curewith X-ray, all within a record time compared to any other knownmethods. Furthermore, the advantage of room temperature bondingminimizes warpage.

Natural Composites:

The present invention permits the fabrication of large wood beams, orother natural composite materials, which has been conventionallyaccomplished, for example, from small wood pieces by resin coating thewood pieces and bonding the assembly under high pressure and heat tocure the adhesive. The present invention's polymerizable adhesivecompositions including the adherent surface structures allow roomtemperature bonding and no moisture needs to be volatized during cure.This is far better than the conventional methods of making suchcomposites which typically use microwaves for heat generation, butcreates enormous amounts of heat in the process, sometimes evenresulting in the workpiece catching fire!

Bonding of Metals:

The present invention permits the bonding of metallic chassis and doorsin automotives (to replace conventional induction heating). Metal sheetscan be bent in special shapes and then adhesively bonded together by thepresent invention's polymerizable adhesive compositions including theadherent surface structures by first forming the adherent surfacestructures and then dispensing a bead of the polymerizable adhesivecomposition around the chassis and mating the metallic pieces, fixingtheir position, followed by curing.

Fluidic Channels:

The present invention permits the creation of fluidic channels inplastics, metals and inorganic substrates by bonding patternedsubstrates together to form said fluidic channels. The joining ofdissimilar plastics, the joining of semiconductors to plastic can bedone by first forming the adherent surface structures and thendispensing the polymerizable adhesive composition onto respectivesurfaces to form and seal the fluidic channels

Multichip Modules:

The present invention permits die on KOVAR substrate, as well as lidsealing on multi-chip-modules to be bonded by first forming the adherentsurface structures and then dispensing the polymerizable adhesivecomposition onto respective surfaces to adhere the die to the KOVAR.

MEMS:

The present invention permits sealing MEMS with glass wafers at roomtemperature (without head shift) can be bonded by first forming theadherent surface structures on the glass wafers and then dispensing thepolymerizable adhesive composition onto respective surfaces to adherethe MEMS and glass wafer together.

Attaching Deformable Substrates, Particularly Dissimilar Substrates:

The present invention permits the attaching rubber to foam, leather torubber, leather to leather, or fabric to fabric, or any combination ofdeformable substrates which can be provided by first forming theadherent surface structures on at least one of the mating surface andthen dispensing the polymerizable adhesive composition onto therespective surfaces to adhere the elements together.

In the description that follows, various aspects of the invention willbe described in greater detail so that the skilled artisan may gain afuller understanding of how the invention may be made and used. Althoughthe present description discusses the use of X-ray as the triggeringradiation for the curing process, other types of ionizing radiation canbe used as the triggering radiation, using similar down-convertingagents, including, but not limited to, gamma rays or particle beams,such as proton beams or electron beams.

CTE—Mismatch

The mismatch between the coefficients of thermal expansion of differentmaterials can be illustrated through the following table. The presentinvention enables joining materials without heat and hence circumventsthe stresses that are typically trapped during thermal heatingnecessitated by thermal curing adhesives. The current invention enablescuring between materials of drastically different CTEs.

TABLE 1 Material Coefficient OF Thermal Expansion/ppm/C Silica Glass 0.6E-Glass 4.8 Alumina 8.7 Steel 14 Aluminum 23-24 Polyimide 38-54 Epoxy45-65 Polyester  55-100 Polystyrene 60-80 Polypropylene  85-200 Siliconeresin 160-180Photoinitiators

Photoinitiators are typically divided into two classes: Type Iphotoinitiators which undergo a unimolecular bond cleavage whenirradiated, yielding free radicals, and Type II photoinitiators whichundergo a bimolecular reaction, in which the excited state of thephotoinitiator interacts with a second molecule (called a coinitiator)to generate free radicals. UV photoinitiators may be of either Type I orType II, whereas visible light photoinitiators are almost exclusivelyType II.

Type I UV photoinitiators include, but are not limited to, the followingclasses of compounds: benzoin ethers, benzil ketals,α-dialkoxyacetophenones, α-aminoalkylphenones, and acylphosphine oxides.Type II UV photoinitiators include, but are not limited to,benzophenones/amines and thioxanthones/amines. Visible photoinitiatorsinclude, but are not limited to, titanocenes.

A large number of useful photoinitiator compounds are known in the art.The following compounds [available from Sigma-Aldrich Corp., St. Louis,Mo.] have been characterized and their UV absorbance spectra areavailable: Acetophenone, 99%; Anisoin, 95%; Anthraquinone, 97%;Anthraquinone-2-sulfonic acid, sodium saltmonohydrate, 97%; (Benzene)tricarbonylchromium, 98%; Benzil, 98%; Benzoin, sublimed, 99.5+%;Benzoin ethyl ether, 99%; Benzoin isobutyl ether, tech., 90%; Benzoinmethyl ether, 96%; Benzophenone, 99%; Benzophenone/1-Hydroxycyclohexylphenyl ketone, 50/50 blend; 3,3′,4,4′-Benzophenonetetracarboxylicdianhydride, sublimed, 98%; 4-Benzoylbiphenyl, 99%;2-Benzyl-2-(dimethylamino)-4′-morpholinobutyrophenone, 97%;4,4′-Bis(diethylamino)benzophenone, 99+%;4,4′-Bis(dimethylamino)benzophenone, 98%; Camphorquinone, 98%;2-Chlorothioxanthen-9-one, 98%; (Cumene)cyclopentadienyliron(II)hexafluorophosphate, 98%; Dibenzosuberenone, 97%;2,2-Diethoxyacetophenone, 95%; 4,4′-Dihydroxybenzophenone, 99%;2,2-Dimethoxy-2-phenylacetophenone, 99%; 4-(Dimethylamino)benzophenone,98%; 4,4′-Dimethylbenzil, 97%; 2,5-Dimethylbenzophenone, tech., 95%;3,4-Dimethylbenzophenone, 99%; Diphenyl(2,4,6-trimethylbenzoyl)phosphineoxide/2-Hydroxy-2-methylpropiophenone, 50/50 blend;4′-Ethoxyacetophenone, 98%; 2-Ethylanthraquinone, 97+%; Ferrocene, 98%;3′-Hydroxyacetophenone, 99+%; 4′-Hydroxyacetophenone, 99%;3-Hydroxybenzophenone, 99%; 4-Hydroxybenzophenone, 98%;1-Hydroxycyclohexyl phenyl ketone, 99%; 2-Hydroxy-2-methylpropiophenone,97%; 2-Methylbenzophenone, 98%; 3-Methylbenzophenone, 99%;Methybenzoylformate, 98%;2-Methyl-4′-(methylthio)-2-morpholinopropiophenone, 98%;Phenanthrenequinone, 99+%; 4′-Phenoxyacetophenone, 98%;Thioxanthen-9-one, 98%; Triarylsulfonium hexafluoroantimonate salts,mixed, 50% in propylene carbonate; and Triarylsulfoniumhexafluorophosphate salts, mixed, 50% in propylene carbonate.

Other suitable photoinitiators include the various IRGACURE productscommercially available from BASF Corporation. The Key Products SelectionGuide 2003 for Photoinitiators for UV Curing is hereby incorporated byreference in its entirety. A representative chemical class ofphotoinitiators is provided as examples. It would be appreciated thatderivatives of such chemistries is also included. The representativelist includes alpha_-Hydroxyketone and derivatives based on(1-Hydroxy-cyclohexyl-phenyl-ketone;2-Hydroxy-2-methyl-1-phenyl-1-propanone;2-Hydroxy-1-[4-(2-hydroxyethoxy) phenyl]-2-methyl-1-propanone).Phenylglyoxylate and derivatives based on (Methylbenzoylformate;oxy-phenyl-acetic acid 2-[2 oxo-2 oxy-phenyl-acetic acid 2-[2 oxo-2phenyl-acetoxy-ethoxy]-ethyl ester and oxy-phenyl-acetic2-[2-hydroxy-ethoxy]-ethyl ester). Benzyldimethyl-ketal and derivativesbased on (Alpha, alpha-dimethoxy-alpha-phenylacetophenone).Alpha-Aminoketone and derivatives based on(2-Benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl) phenyl]-1-butanone;2-Methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone/IRGACURE369 (30 wt %)+IRGACURE 651 (70 wt %). Mono Acyl Phosphine (MAPO) andderivatives based on (Diphenyl (2,4,6-trimethylbenzoyl)-phosphine oxide.MAPO alpha-Hydroxyketone and derivatives based on DAROCUR TPO (50 wt%)+DAROCUR 1173 (50 wt %). Bis Acyl Phosphine (BAPO) and derivativesbased on Phosphine oxide, phenyl bis (2,4,6-trimethyl benzoyl). BAPODispersion based on (IRGACURE 819 (45% active) dispersed in water).BAPO/alpha_-Hydroxyketone (IRGACURE 819 (20 wt %)+DAROCUR 1173 (80 wt%). Metallocene (Bis (eta 5-2,4-cyclopentadien-1-yl), Bis[2,6-difluoro-3-(1H-pyrrol-1-yl), phenyl]titanium). Iodonium salt andderivatives based on Iodonium, (4-methylphenyl) [4-(2-methylpropyl)phenyl]-, hexafluorophosphate(1-).

The polymerizable adhesive composition of the present invention cancomprise a polymerizable composition or a crosslinkable composition. Theterm organic vehicle is used herein to indicate the portion of thecurable adhesive composition that ultimately forms the resin uponcuring, whether by polymerization or crosslinking. Thus, a polymerizableorganic vehicle comprises at least one polymerizable monomer. Acrosslinkable organic vehicle thus comprises a plurality ofcrosslinkable polymer chains. Ideally, the organic vehicle is of asuitable viscosity for dispensing/applying to the desired substrate.

The monomer system may be selected based upon overall requirements suchas strength, flexibility or compliance, matching with substrateproperties, and the type of bonding involved, such as electricallyconductive bonding versus a strictly structural adhesive bond.

Some suitable monomer systems that may be used for various applicationsof the invention include, without limitation: epoxies, phenolics,urethanes, acrylics, cyanoacrylates, silicones, polysulfides,polyimides, polyphenylquinoxalines, and styrenes. UV-light curingacrylic adhesives and UV-light curing silicones are commerciallyavailable.

Accordingly, in various embodiments of the present invention, themonomer systems and photoinitiators noted above bonds to the adherentstructures described herein to promote the bond between two or moresubstrates. In various embodiments of the present invention, the monomersystems and photoinitiators noted above include the down converters andup converters described herein.

Energy Converting Materials

Many other downconverting particles, upconverting particles, plasmonicsactive particles and combinations of these are disclosed in U.S.provisional patent application 61/161,328, filed Mar. 18, 2009; U.S.provisional patent application 61/259,940, filed Nov. 10, 2009; U.S.Provisional Application Ser. No. 60/954,263, filed Aug. 6, 2007, and61/030,437, filed Feb. 21, 2008; U.S. application Ser. No. 12/059,484,filed Mar. 31, 2008; U.S. application Ser. No. 11/935,655, filed Nov. 6,2007; U.S. Provisional Application Ser. No. 61/042,561, filed Apr. 4,2008; 61/035,559, filed Mar. 11, 2008; and 61/080,140, filed Jul. 11,2008; U.S. patent application Ser. No. 12/401,478 filed Mar. 10, 2009;U.S. patent application Ser. No. 11/935,655, filed Nov. 6, 2007; U.S.patent application Ser. No. 12/059,484, filed Mar. 31, 2008; U.S. patentapplication Ser. No. 12/389,946, filed Feb. 20, 2009; and U.S. patentapplication Ser. No. 12/417,779, filed Apr. 3, 2009, the entiredisclosures of each of which are hereby incorporated by reference.

Phosphor selection criteria were based on peak intensity of theemission, peak position with UV of the emission, the need to have aworkable phosphor with minimal storage requirements, handling andpackaging, the ability of the phosphor to couple to X-ray energy, thecontrol over its particle size and particle size distribution; and,finally their surface chemistry.

The peak emission target is between 310 nm and 400 nm or simply the UVAspectrum. It is desirable to have the maximum conversion of X-rayintensity into UVA intensity. This conversion described in variousinterrelated terms. Sometimes it is referred to as the quantum yield orprobability of interaction between X-ray and phosphors. Theseinterrelated terms include the coupling efficiency, emissioneffectiveness or the Effective-Z between the X-ray and the phosphor. Alist of some of the best X-ray phosphors is reported in Table 2.

TABLE 2 Emission Spectrum X-ray Absorption Microstructure Peak EmissionEmiss Eff K-edge Specific Crystal # Phosphor (nm) (%) Eff (Z) (keV)Gravity Structure Hygroscopic 1 BaFCl:Eu²⁺ 380 13 49.3 37.38 4.7Tetragonal N 2 BaSO₄−:Eu²⁺ 390 6 45.5 37.38 4.5 Rhombic N 3 LaOBr:Tm³⁺360, 460 14 49.3 38.92 6.3 Tetragonal N 4 YTaO₄ 337 59.8 67.42 7.5Monolithic N 5 YTaO₄:Nb (*) 410 11 59.8 67.42 7.5 Monolithic N 6 CaWO₄420 5 61.8 69.48 6.1 Tetragonal N 7 LaOBr:Tb³⁺ 420 20 49.3 38.92 6.3Tetragonal N 8 Y₂O₂S:Tb³⁺ 420 18 34.9 17.04 4.9 Hexgonal N 9 ZnS:Ag 45017 26.7  9.66 3.9 Hexgonal N 10 (Zn,Cd)S:Ag 530 19 38.4 9.66/26.7 4.8Hexgonal N 11 Gd₂O₂S:Tb³⁺ 545 13 59.5 50.22 7.3 Hexgonal N 12La₂O₂S:Tb³⁺ 545 12.5 52.6 38.92 6.5 Hexgonal N

Accordingly, in various embodiments of the present invention, the energyconverting materials noted above activate the photoinitiators notedabove to affect curing of the adhesive medium between two or moresubstrates. In other embodiments, the energy converting materialspromote curing or vulcanization of the natural or synthetic rubbercompounds noted above.

UVA/UVB Emissions

In some applications the desirable incident or initiation energy isdifferent than X-ray (such as EUV) while the desirable down-convertedoutput intensity remains in the UVA. In other applications the desirableincident or initiation energy is X-ray but the desirable down-convertedenergy output of the phosphor is in the UVB. Yet in other cases thedesirable incident or initiation energy is X-ray but the desirabledown-converted energy output of the phosphor is in the UVA and the UVB.The selected phosphors were selected to work with excitation sourcesincluding X-ray, extreme UV and e-beam. Within the X-ray regime, theselected phosphors can couple to a flux of X-ray photons emanating fromcommercially available equipment sources used for therapeutic tumortreatments, medical imaging and semiconductor inspection.

An example of a material that emits in the UVA regime is provided inFIG. 2A. The X-ray system used to carry out the experiment was theFaxitron X-ray System. An example of a material having an output in theUVB is provided in FIG. 2B. An example of a material having an output inthe UVA, UVB and the visible is provided in FIG. 3.

Accordingly, in various embodiments of the present invention, thephosphors noted above activate the photoinitiators noted above toproduce UV light and affect curing of the adhesive medium between two ormore substrates. In other embodiments, the phosphors promote curing orvulcanization of the natural or synthetic rubber compounds noted above.

Mixed or Alloyed Phosphors

Another possibility of interest is the ability to mix at least twophosphors to broaden the output of the mixture compared with thestarting phosphors. In this example, two phosphors each emitting in adistinct region were mixed together and the output spectral output wasmeasured to demonstrate the ability to influence the output intensity ofthe mixture compared to the starting materials. (See FIGS. 4 and 5)

The intensity of the initiation energy (X-ray in this case) influencesthe UV output of the phosphor. The following examples are provided toillustrate how modifying the intensity of photonic energy of X-ray canmodulate the light output of the X-ray. The relative intensity output ofa phosphor (CaOW₄) was measured as a function of the energy of the X-rayphotons. The X-ray energy was modified by modifying the peak voltagesthat exist between the filament and the target. The target in this casewas tungsten. The measurements were carried out using the same mass ofphosphor under 50 kVp, 90 kVp and 130 kVp. The relative intensity of theemission in arbitrary units is indicative but not conclusive in terms ofcomparing different materials. However, within the same conditions usedto conduct measurements, it is clear that the higher X-ray intensity thehigher the relative intensity of the emitted wavelength. (See FIG. 6)

The phosphors can be synthesized from different chemicals and usingdifferent processes to control their morphology, influence theirproperties and light intensity output but more importantly theirstability in ambient air environments. It is preferred to have phosphorsthat are not hygroscopic. Phosphors are easier to handle and to workwith when they are stable in water and do not contain dopants that aretoxic; however, even when phosphors are not stable in water and docontain dopants that are toxic, the particles of the phosphors can becoated using chemistry synthesis methods that leads to the build-up of aprotective coating which shields the phosphor from the environment(water for example) and shields the environment from the toxic dopant inthe phosphor (bromide for example). The protective coating can be silicaor can be diamond or diamond-like carbon. Silica can be formed usingsol-gel derived techniques. Diamond and diamond-like carbon can bederived from chemical vapor deposition (CVD) based on hydrogen-methanegas mixtures. Handling and packaging of phosphors can be achievedthrough dispersion in solution or in powder form. It was found thatsilica coated phosphors make a good powder that does not agglomerate.

In addition to high intensity, emission at the correct wavelengths,another desirable attribute of phosphors is to have low specific gravity(if possible). A low specific gravity may help avoid sedimentation andsettling when the phosphors are mixed into another media such as a resinor a resin blend containing photo-initiators.

Accordingly, in various embodiments of the present invention, the mixedphosphors noted above activate the photoinitiators noted above to affectcuring of the adhesive medium between two or more substrates. In otherembodiments, the mixed phosphors promote curing or vulcanization of thenatural or synthetic rubber compounds noted above.

Rheology Adjustment

The particle size of the phosphor is a relevant factor. The smaller theparticle size the higher the surface area. The small particles werefound to alter the rheology of resins containing photo-catalysts moreeffectively than larger phosphor particles. The larger the particlessize the higher the intensity output. The phosphors were found toperform well in terms of conversion of X-ray into UVA and activatingphoto-catalysts inside resin systems when they contain a particle sizedistribution (not a mono-modal particle size distribution). Thephosphors having small particles (i.e. having a high surface area) weresuccessfully used to increase the viscosity of the resin without the useof active silica (or AEROSIL). In one embodiment, phosphornano-particles are added to adjust viscosity in-lieu of active silica.The best photo-activation and viscosity adjustment was found whennano-particles were used with a phosphor having particles up to the 5microns particle size. In essence bimodal distribution of particles canhelp the packing factor (or loading content of phosphors into the resin)as well as helps in terms of rheological control and UVA light intensitygeneration for the formulation of adhesives having controllableviscosity, good curing under X-ray. A tri-modal or large distribution ofparticle sizes are effective in balancing rheology of the adhesive andcure response of the adhesive under X-ray.

Organic Materials

In addition to the inorganic compounds (or phosphors) described in thecurrent invention, organic compounds can be used to achieve the same ora similar purpose to affect curing of the adhesive medium between two ormore substrates or to promote curing or vulcanization of the natural orsynthetic rubber compounds noted above. For example, anthracene andanthracene based compounds can be used to achieve the objective of theinvention (curing with no line of sight and thermal energy). Anthraceneexhibits a blue (400-500 nm peak) fluorescence under ultraviolet light.Furthermore, it was found that anthracene exhibits fluorescence underX-Ray energy.

Various plastic scintillators, plastic scintillator fibers and relatedmaterials are made of polyvinyltoluene or styrene and fluors. These andother formulations are commercially available, such as from Saint GobainCrystals, as BC-414, BC-420, BC-422, or BCF-10.

TABLE 3 Product Peak Emission Phosphor Reference (nm) Organic BC-414 392Organic BC-420 391 Organic BC-422 370

Other polymers are able to emit in the visible range and these include:

TABLE 4 # of Phosphor Product Peak Emission Photons Per (Fiber Forms)Reference (nm) MeV Organic BCF-10 432 8000 Organic BC-420 435 8000Organic BC-422 492 8000

Furthermore, these organic compounds that can convert X-ray to UV energycan be interwoven into synthetic polymer chains. Here, the plasma orchemical treatments described above may be an excellent way to form theadherent structures on the into synthetic polymer chains to permitbinding and adhesion. These chains can be used as the base resin systemfor a cross-linking adhesive; hence leading to the formation of a newset of X-ray activatable resin systems.

UV receptive chemistries can be made more reactive by addingphoto-sensitizers. This process is referred to as photo-sensitization.Certain photosensitive chemical compounds can be added to supplementphotonic energy to the reactant and the reactant site to promote orenhance curing.

For UV curing applications, it is of interest to have chemistries thatupon exposure to the UV radiation would form an intermediate in anexcited state that in turn emits light of the correct wavelength forfurther curing to take place. In other words, a sensitizer plays a rolein energy transfer.

Many light sensitizing chemistries are known and widely used in theindustry and these include to name but a few, acenaphthene quinone,aceanthrene quinone, or a mixture thereof with anthrone and/ornaphthoquinone, violanthrone, isoviolanthrene, fluoresceine, rubrene,9,10-diphenylanthracene, tetracene, 13,13′-dibenzantronile, levulinicacid.

Accordingly, in various embodiments of the present invention, theorganic phosphors noted above activate the photoinitiators noted aboveto affect curing of the adhesive medium between two or more substrates.In other embodiments, the organic phosphors promote curing orvulcanization of the natural or synthetic rubber compounds noted above.

Spectral Matching

Table 5 shows a wide variety of energy modulation agents which can beused in this invention.

TABLE 5 Emission X-Ray Spectrum Absorption Phosphor Peak Emission EmissEff K-edge Specific Crystal Item # Color (nm) (%) Eff (Z) (keV) GravityStructure Hygroscopic 24 Zn3(PO4)2:Ti+ 310 N 33 BaF2 310 Slightly 30 CsI315 N 23 Ca3(PO4)2:Ti+ 330 N 4 YTaO4 337 59.8 67.42 7.5 Monolithic N 38CsI:Na 338 Y 14 BaSi2O5:Pb2+ 350 N 27 Borosilicate 350 N 34 LaCl3(Ce)350 Y 16 SrB4O7F:Eu2+ 360 N 20 RbBr:Tl+ 360 ? 15 (Ba,Sr,Mg)3Si2O7:Pb2+370 N 17 YAlO3:Ce3+ 370 N 37 BC-422 370 Organic ? 1 BaFCl:Eu2+ 380 1349.3 37.38 4.7 Tetragonal N 2 BaSO4−:Eu2+ 390 6 45.5 37.38 4.5 Rhombic N19 BaFBr:Eu2+ 390 ? 36 BC-420 391 Organic ? 35 BC-414 392 Organic ? 25SrMgP2O7:Eu2+ 394 N 18 BaBr2:Eu2+ 400 N 22 (Sr,Ba)Al2Si2O8:Eu2+ 400 N 5YTaO4:Nb (*) 410 11 59.8 67.42 7.5 Monolithic N 21 Y2SiO5:Ce3+ 410 N 6CaWO4 420 5 61.8 69.48 6.1 Tetragonal N 7 LaOBr:Tb3+ 420 20 49.3 38.926.3 Tetragonal N 8 Y2O2S:Tb3+ 420 18 34.9 17.04 4.9 Hexgonal N 13Lu2SiO5:Ce3+ 420 N 26 Lu1.8 Y0.2SiO5:Ce 420 N 9 ZnS:Ag 450 17 26.7 9.663.9 Hexgonal N 29 CdWO4 475 Slightly 28 Bi4Ge3O12 (BGO) 480 N 10(Zn,Cd)S:Ag 530 19 38.4 9.66/26.7 4.8 Hexgonal N 11 Gd2O2S:Tb3+ 545 1359.5 50.22 7.3 Hexgonal N 12 La2O2S:Tb3+ 545 12.5 52.6 38.92 6.5Hexgonal N 31 Y3Al5O12 (Ce) 550 N 3 LaOBr:Tm3+ 360, 460 14 49.3 38.926.3 Tetragonal N 32 CaF2(Eu) 435/300 N

It will be appreciated that the most efficient system will be one inwhich the particular photo-initiator is selected based on itsabsorption, its photo-catalysis sensitivity to the intensity of theincident radiation (i.e.; the efficiency of energy transfer).

The emission wavelength in many embodiments of the present inventiondepends on the particular down converter material chosen to carry outthe cure of the photo-catalytic reaction under consideration.Accordingly, to ensure the most efficient energy transfer from thephosphor to the photoinitiator, the phosphors are paired with thecorrect photoinitiators to match the emitted frequency/wavelength fromthe down-converter material to the peak absorption of thephoto-initiator. This is referred to as a spectral match in the currentinvention. The spectral matching mentioned above increases the chancesof successful attempts needed to overcome the activation energy barriergating reactions. Table 6 shows the relative peak absorption of certainphoto-initiators and the relative peak emissions of certain phosphors.The pairing of photo-initiators and phosphors was done accordingly tothe table and successfully demonstrated as illustrated in the examples.

TABLE 6 Photoinitiator Absorption Peaks Peak Absorption Phosphor PeakEmission IRGACUR 784 398, 470 398 LaOBr:Tm3+ (coated) 360, 460 DAROCUR4265 240, 272, 380 380 CWO4:Pb 425 IRGACUR 2100 275, 370 370 YTaO4:Nb(*) 410 IRGACUR 2022 246, 282, 370 370 Y2SiO5:Ce 410 IRGACUR 819DW 295,370 370 BaSO4−:Eu2+ (coated) 390 IRGACUR 819 295, 370 370 SrB6O10:Pb 360DAROCUR TPO 295, 368, 380, 393 368 BaSi2O5:Pb2+ 350 IRGACURE 651 250,340 340 CsI:Na (Coated) 338 IRGACURE 184 246, 280, 333 333 YTaO4 337IRGACURE 500 250, 332 332 DAROCUR 1173 245, 280, 331 331 IRGACURE 754255, 325 325 DAROCUR MBF 255, 325 325 IRGACURE 369 233, 324 324 IRGACURE1300 251, 323 323 IRGACURE 907 230, 304 304 IRGACURE 2959 276 270

Accordingly, in various embodiments of the present invention, thespectrally-matched phosphors (inorganic or organic) noted above activatethe photoinitiators to affect curing of the adhesive medium between twoor more substrates. In other embodiments, the spectrally-matchedphosphors (inorganic or organic) promote curing or vulcanization of thenatural or synthetic rubber compounds noted above.

Phosphor and Photo-Initiator Design Factors

Furthermore, the distance between a phosphor particle and aphoto-initiator influences the efficiency of energy transfer. Theshorter the distance between the photo-initiators and the phosphors thebetter chances of energy transfer leading to successful reactions willtake place. Inside a mixture of a curable system there are manyparticles and a relatively elevated concentration of photo-initiators.As a result, there is more than one distance between particles andphoto-initiators. In these cases, the average distance between phosphorparticles and photo-initiators is used a metric, but other distancemetrics could be used.

The photo-initiators can be attached onto the surface of phosphorparticles using tethering of adsorption techniques among others. In thecase of tethering, a high vs. low molecular weight would be an effectiveway to change the distance between the photo-initiators and theparticles respective surfaces. In the case of deposition throughadsorption, the distance between the surface of the phosphors and thephoto-initiators can be altered by inner-layering a coating that istransparent to the radiation emitted by the phosphors. SiO₂ is anexample of such inner layer since it is transparent to UV.

Packing factor and average distance between the phosphors and thephoto-initiators can be impacted using a surface coating. The packingfactor of a phosphor having innate surface chemistry would therefore bedifferent than that for a phosphor having a relatively thick coating.

The combination of the spectral match defined above, the averagedistance between the photo-initiators and the phosphors, the intensityof radiation generated by the phosphor particles under an initiationradiation, the particle size distribution constitutes the most efficientembodiment of the present invention.

In regards to the packing factor of the phosphors, a large enough silicacoating deposited on the surfaces of particles would change theeffective packing factor of effective density of the powder (i.e.; massper unit volume of powder). Similarly, a phosphor coated with a coatinghaving an irregular shape can further influence the mass per unitvolume. As an example a powder of an average particle size of 5 micronscan be coated with a enough silica to obtain an average size of 15microns.

The phosphor itself becomes more or less responsive to the incidentX-ray beam as a result of the coating that can alter its effectivedensity of the mass of the powder per unit volume. The probability ofinteraction between the X-ray energy and the phosphors decreases withincreasing coating wall thickness. An illustration is provided in FIG. 7where the same amount of phosphor (i.e.; the X-ray coupling agent) canoccupy a larger thickness.

By virtue of changing the concentration of phosphor or by changing theeffective packing factor of the phosphor, the probability of interactionof the X-ray energy with the phosphor filled resin can be altered. Theintensity of X-ray can be attenuated differently between a phosphor thathas a coating and an innate phosphor surface (see FIG. 8).

As noted above, in one embodiment of this invention, organic phosphorscan be used having a significantly smaller size than conventioninorganic polymers.

The coated phosphors can be used as the filler in the resin system. Thewidely used filler in the industry is silica. In some cases alumina andboron-nitride are used. The silicate fillers are used to substitute someof the resin volume without degrading the properties of curablematerial. The filling of silica powder leads to cost savings. Filledsystems are typically more mechanically stable and more cost effectivethan the unfilled systems.

Accordingly, in various embodiments of the present invention, the coatedphosphors (inorganic or organic) noted above activate thephotoinitiators to affect curing of the adhesive medium between two ormore substrates. In other embodiments, the coated phosphors (inorganicor organic) promote curing or vulcanization of the natural or syntheticrubber compounds noted above.

Cure Categorization:

The UV curing materials can be diverse; but, as a generalcategorization, the following materials sets are outlined by specificresin families, associated initiators, cure mechanism and appropriateapplication. This is by no means an inclusive list but just a generalcategorization to further illustration. The present invention iscompatible with each of these categories including radical cross-linkingor polymerization, cationic crosslinking, base catalyzed crosslinking.

Direct X-Ray Cure:

Direct curing with x-ray energy (with or without the use of phosphors)is also possible in the present invention. For example, one can add achemical compound that has the capability of being activated directlyunder x-ray energy, such as methyl ethyl ketone peroxide (MEKP), whichis an organic peroxide, to assist in initiating the polymerization.Also, benzoyl peroxide, another compound in the in the peroxide familythat has two benzoyl groups bridged by a peroxide link, can be used toassist in the initiation of the polymerization under x-ray. The effectof phosphors and these peroxide based chemicals can be additive.

Co-Curing

In some applications it is useful to have two adhesive beads. Oneadhesive bead is filled with a phosphor having a high effective packingdensity and another adhesive bead having a lower packing density. Inthis case, under the same X-ray energy intensity, one bead would curefaster than the other. In some dam and fill applications, such as inRF-ID, one could apply a dam, cure it, and then fill and cure the fill.(See FIG. 9) However, one could co-cure the 2 adhesive beads using themethod described here by the ability to couple more initiation energyinto the containment bead as compared with the filler. These methodsallow the curing of the containment bead and the filler material at thesame time (co-curing) or curing one after the other (sequential curing).The same base adhesive can be used for both cases (possibly the samechemical formulation) with the containment bead having a phosphor of adifferent conversion efficiency than that of the filler material. Thiscan be readily done by proper choice of the phosphor, or content of thephosphor. In a way the adhesive beads can be cured effectively at thesame time but one sees more UV intensity than the other and cure fasterthan the other under the same X-ray beam.

Yet in another embodiment of the present invention, an insertion moldedpiece of plastic containing the appropriate amount of phosphor is addedas part of the material to be cured. (See FIG. 10) As a molded framethis acts as the source of UV under X-ray energy. In this case theinserted molded piece gives extra UV energy to the dam (or perimeterarea) and leads to faster curing. This allows the materials to cure moreselectively at the borders. This example describes the usefulness ofinsertion molding as described in FIG. 10.

In one embodiment of the present invention, the polymerizable adhesivecompositions including the adherent surface structures are utilized toimprove and enhance the bonding strength.

Additionally photo-sensitizing chemistries can be used to enhance thephoto-catalytic based reactions.

Accordingly, in various embodiments of the present invention, the lightactivated curing of the adhesive medium between two or more substratescan be assisted by other curing mechanisms. In other embodiments, thecuring or vulcanization of the natural or synthetic rubber compoundsnoted above can be assisted by the other curing mechanisms.

Sol Gel Coating

Surface Modification for Special Phosphors.

Synthesizing phosphors in the micron and nanometer particle sizes can bedone using various methods. Also various phosphors may have differentsurface chemistries. Some phosphors could be potentially hygroscopic ortoxic in high doses. One way to enable the use of hygroscopic orpotentially toxic phosphors is to form a containing barrier layer aroundphosphor particles. This has the double benefit of standardizingdifferent phosphor chemistries to have the same common surface chemistrywith predictable behavior as well as shield the phosphor inside abarrier layer. A sol-gel derived silicate coating is one method by whichthis can be achieved. Silica happens to be UV transparent and iscongruent with most oxides and most phosphors that are not hygroscopic(as listed in the phosphor table).

The protective coating can be silica or can be diamond or diamond-likecarbon. Silica can be formed using sol-gel derived techniques. Diamondand diamond-like carbon can be derived from CVD based onhydrogen-methane gas mixtures. These are but representative examples ofthe methods that are possible.

Dispersion:

The uniform distribution of phosphors inside a curable system influencesthe homogeneity of the curable material and therefore the mechanical andoptical properties of the curable material. The mixing uniformity andthe particles size distribution have an influence on the curing systemresponse in terms of cure extent as a function of time under theinitiation energy. The uniformity of the dispersion can be short livedif the phosphors have a high specific density leading to settling in theresin.

Dispersants

The surface of the phosphors can be modified for two general purposes.One method leads to tethering or adsorbing the photo-initiators onto thesurface of the phosphors. The other method is to add dispersantchemistries to the surface of phosphors to enable the phosphors toremain in suspension after the adhesive is formulated and theingredients have been mixed together. In general phosphors are preferredto be in powder form with minimal aggregation between particles. Thedispersion of phosphor powder in a resin system can be achieved usingvarious methods. These dispersion methods keep the phosphors insuspension by limiting or preventing the potential re-flocculationcaused by the particles' Brownian motion at room temperature or attemperatures above room temperatures by 20° C. to 30° C. These slightlyelevated above room temperature are useful in dispensing the adhesivesthrough a needle using a piston or an auger pump.

The surface modification of the phosphors to maintain a uniformdispersion after mixing is important. Various organic polymer agents canbe used to increase the wetting characteristics of the phosphors intothe resin chemistry. Similarly, various dispersing agents can be addedto maintain the phosphor particles in suspension inside the mix. Thedispersing agents are built from polyurethane or polyacrylate polymericstructures having high molecular weight (3000-50000). Various dispersingagent are available in the market. The dispersants can be anchored ontoinorganic surface by virtue of surface charge (the electrostaticattraction of oppositely charged surfaces) and can be anchored oradsorbed to the organic substances like the chains in the resin byvirtue of dipolar interactions, hydrogen bonding andLondon/van-der-Waals forces. Once anchored in place the high molecularweight dispersants increase the steric hindrance for particles todiffuse too close to one another hence preventing agglomeration ofphosphors.

Tethering

The downconverting particles and photo-initiators used in the presentinvention can be added as separate components to the curable adhesiveformulation, or can be tethered to one another to provide increasedlikelihood of activation of the photoinitiator upon emission from thedownconverting particles. Tethering of photoinitiators to thedownconverting particles can be done by any conventional chemistry, solong as it does not interfere with the emission characteristics of thedownconverting particles (other than potential slight movement of thepeak emission in the red or blue direction), and so long as it does notinterfere with the ability of the photoinitiator to initiatepolymerization of the curable adhesive composition. One may also usecombinations of two or more phosphors, two or more photoinitiators, orboth, to achieve more complex curing kinetics. Further, one can useorganic downconverters, such as anthracene, rather than the variousinorganic downconverters noted above. With the organic downconverters,there are additional possibilities including, but not limited to, use ofthe organic downconverter material as a separate component in thecurable adhesive composition, tethering the organic downconverter to thephotoinitiator, as described for the inorganic downconverter particlesabove, or even incorporation of the organic downconverter groups intoone or more of the monomer components of the curable adhesivecomposition.

One suitable chemistry for tethering inorganic down converter particlesto the photoinitiator is shown in FIG. 17, whereby a silica coatedphosphor is reacted with aminopropyltriethoxysilane (APTES), then themodified photoinitiator is bound to the pendant aminopropyl group.

Other possible modifications include, but are not limited to, thefollowing:

-   -   a. Modification of existing adhesives by adding special        downconverting particles from X-ray to UV in the range of        susceptibility of a Photoinitiator

Accordingly, in various embodiments of the present invention, the coatedand/or tethered phosphors noted above activate the photoinitiators toaffect curing of the adhesive medium between two or more substrates. Inother embodiments, the coated and/or tethered phosphors promote curingor vulcanization of the natural or synthetic rubber compounds notedabove.

Building Composited Particles

In applications that require the use of micron level particles that arecost effective down converters, the surface of a carrier particle madeof silica can be decorated with desirable phosphors with nanometerparticle size. The phosphors are chosen for the right emission UVwavelength and intensity under X-ray.

The downconverting particle comprises a composite of nanoparticles and asilicate carrier particle. The silicate carrier particle has the samesurface characteristics as a particle typically used as a filler(including silica). In this case the down converting particles arebonded to the surface of the base carrier particle followed by a coatingas shown in FIGS. 11A and 11B.

By way of illustration the construction of such a composite particle ishereby provided. This description is non-inclusive of all thepossibilities but provides one viable synthesis method.

The core or carrier particle can be made of glass, such as SiO₂ oralkali-lead-silicate and have a diameter of about 2 microns.Nanometer-scale downconverting particles are applied to the surface ofthe core particle, and subsequently made to adhere or bond to thesurface of the core particle (see FIG. 11B). Some of the methodsenabling this bonding process include precipitation techniques from asolution. Another method is based on condensation by heating thedownconverting particles to much elevated temperatures compared to thecore particles while maintaining the silicate based particles abovetheir softening point. At the correct respective ranges of temperature,which are readily determined by one of ordinary skill in the art basedon the compositions of the core particle and downconverting particlechosen, the downconverting particles and the carrier particles areforced into contact, leading to condensation, thus allowing surfacedeposition to take place. The downconverting particles can be any of thephosphors listed in Table 5 or elsewhere described herein.

Accordingly, in various embodiments of the present invention, thecomposite phosphor particles noted above activate the photoinitiators toaffect curing of the adhesive medium between two or more substrates. Inother embodiments, the composite phosphor particles (inorganic ororganic) promote curing or vulcanization of the natural or syntheticrubber compounds noted above.

Quantum Dots and Alloyed Derivatives—

The downconverting particles, for example, can be quantum dots with thesuitable range of downconversion from X-ray to UV. The quantum dotsand/or oxides used for the downconversion process can further compriseelements, or alloys of compounds or elements tuned for plasmonicactivity (see FIG. 12). In a preferred embodiment, the quantum dotspreferably comprise a mixture of zinc sulfide and zinc selenide, morepreferably in a ratio within a compositional window of 60% zinc sulfide,40% zinc selenide to 70% zinc sulfide, 30% zinc selenide. The metalalloys used for plasmonics comprise silver/gold mixtures, morepreferably within the compositional window of 60% silver and 40% gold,to 70% silver and 30% gold.

After the carrier core particle is decorated with the down convertingparticles, coating the outer layer is desirable to encapsulate andprotect the down converting particles as well as modify the surface. Theouter layer coating can be accomplished using sol-gel processingfollowed by heat treatment. This leads to the formation of a compositedparticle consisting of a core particle with down-converting particles onthe surface and the whole is coated with a silicate coating. (see FIG.13). This special filler particle is used to replace an existing fillermaterial.

Accordingly, in various embodiments of the present invention, thequantum dot structures noted above activate the photoinitiators toaffect curing of the adhesive medium between two or more substrates. Inother embodiments, the quantum dot structures promote curing orvulcanization of the natural or synthetic rubber compounds noted above.

Tethering to Composite Particles

The present invention includes special provisions for a modified use ofexisting photoinitiators by tethering the photoinitiator tonanoparticles having downconverting properties. This close proximity ofnanoparticle to photoinitiator maximizes the chance for photoinitiationor photo-catalysis, and can achieve improved cure efficiencies. (seeFIG. 14)

In the tethered case, the downconverting particles are added duringmixing an adhesive preparation using tethered particles on a carrierparticle and mixing into the adhesive. As an alternative embodiment, thetethered photoinitiator and downconverting particles can be positionedon the surfaces of micron level carrier particles. (See FIGS. 15A and15B) The carrier particles are then used as filler. This time no surfacecoating is necessary and the photoinitiator is in direct contact withthe resin. (FIG. 15A). Alternatively, this arrangement can also use acoating of SiO₂, on which are tethered the photoinitiators. (FIG. 15B).

Since in this particular embodiment, micron size particles (largeparticles) are added to the mix, the impact on adhesive rheology isminimized compared to adding nano-size particles. This method can thuspresent added advantages, including the ability to use the micron sizeparticles as a filler to otherwise alter the cured adhesive or polymerproperties.

Accordingly, in various embodiments of the present invention, thetethered composite energy modulators noted above activate thephotoinitiators to affect curing of the adhesive medium between two ormore substrates. In other embodiments, the tethered composite energymodulators promote curing or vulcanization of the natural or syntheticrubber compounds noted above.

Composite Particles

Achieving brighter luminescing particles can be done by having thecarrier particle decorated with two layers of phosphors. First thecarrier particle is decorated with nano-sized phosphors (FIG. 16A), thencoated using sol gel derived silica and lastly decorated a second timewith phosphors of the correct size (FIG. 16B). This technique can berepeated to obtain more phosphors or down conversion particles at theouter-layers of the carrier particles.

Accordingly, in various embodiments of the present invention, thecomposite phosphor structures noted above activate the photoinitiatorsto affect curing of the adhesive medium between two or more substrates.In other embodiments, the composite phosphor structures promote curingor vulcanization of the natural or synthetic rubber compounds notedabove.

GENERALIZED ASPECTS OF THE INVENTION

The present invention reactive chemistries located across an interfacebetween two substrates preferably are complimentary and reactive to oneanother. In one preferred embodiment, the reactive chemistries of thepresent invention can form the surface of one or both substrates, anadherent structure which can result in bonding one layer to the otheracross the interface. In an alternate embodiment, an adherent structurecan be used which reacts with each substrate surface independently toaffect the bond between the layers. In a further embodiment, thesubstrate surfaces are coated with reactive chemistry such as thenatural and/or synthetic rubber compounds noted above, which results inreactive moiety formation, and the creation of chemical bonds (anadherent structure) to the surface, and between the coatings on eachsurface. In the present invention, the application of X-ray radiation tothe novel chemistry causes the formation and/or release of a catalyst atthe bonding interface.

The present invention relates to reactive chemistries and associatedmethods of use to bond two substrates across their interface underX-Ray, e-beam and UV radiation, wherein the reactive chemistries reactby way of a mechanism including, but not limited to, radical formation(which can be by hydrogen or other atom or group abstraction, chainscission, or any other mechanism forming radicals), cation or anionformation, photo-initiation, and a combination of two or more of theabove in the absence of line-of-sight. These mechanisms forming anadherent structure to which a curable resin can adhere, therebyproviding a mechanism to bond even low energy surfaces together.

The present invention methods are used for bonding two or moresubstrates together wherein the bond formation at the interface betweentwo substrates is achieved without the requirement of UV activation orthermal heating. However, in an alternate embodiment, either or both ofUV activation and thermal heating can be used in some cases to assist inthe achievement of better bonding properties, as desired.

Within the context of the present invention, the term “substrate” or“substrates” is used merely to refer to an object being acted upon inthe present invention method, such that the bonding of two substratescauses at least one surface of a first substrate to bond to at least onesurface of a second substrate. While the method is described withrespect to bonding two substrates to one another, it is possible to usethe present invention method to simultaneously, or sequentially, bondmultiple substrates to one another, depending on the final structuredesired.

In this invention, substrates are caused to form a bond either directlyor indirectly under the application of X-Ray energy, e-beam or acombination of UV and X-Ray and e-beam energy. In the present invention,these sources of energy can operate interchangeably, depending on thechemistry used.

In the case of the direct bond formation between two substrates, thechemistries of the two substrates is modified and made to include thenovel reactive chemistries at their interfaces (such as the naturaland/or synthetic rubber compounds noted above with or without energyconverters) to form an adherent structure. The novel reactivechemistries can be disposed at the interface of the two substrates byvirtue of being interwoven (or blended) in the composition of theobjects or can be applied as a surface modification or coating on thesurface of the substrate to be bonded (an adherent structure). In thecase where one substrate is made of a polymer material, the reactivechemistry may be blended in as a co-polymer. The substrates can be madeof any material, including, but not limited to, polymers and plastics,glass, ceramics, metals, metal oxides, etc.

In the case of indirect bond formation between two substrates, a layerof the present invention chemistry is applied either to one or bothsubstrate surfaces to be bonded, or as a separate layer in the interfaceformed between the two substrate surfaces to be bonded, followed bypressing the objects together and exposing the thus formed assembly toX-Ray energy or other high energy penetrating radiation. The layer ofthe present invention chemistry is preferably applied as a conformablecoating or as a conformable film.

The present invention reactive chemistries are capable of beingactivated by X-Ray energy and or the combination of X-Ray and UVradiation. In embodiments that use UV radiation, when line-of-sight isnot possible, or when the substrate material is not UV transmissive, theUV radiation at the interface of the two substrates in the presentinvention is generated through the down conversion of X-Ray energy intoUV energy enabled by energy modulating agents, preferably in particleform. Suitable energy modulation agents and particles are disclosed inU.S. application Ser. No. 12/764,184, filed Apr. 21, 2010; U.S.application Ser. No. 12/763,404, filed Apr. 20, 2010; U.S. applicationSer. No. 12/843,188, filed Jul. 26, 2010; U.S. application Ser. No.12/891,466, filed Sep. 27, 2010; U.S. application Ser. No. 12/943,787,filed Nov. 10, 2010; U.S. application Ser. No. 13/054,279, filed Jul.13, 2011; U.S. application Ser. No. 13/102,277, filed May 6, 2011; U.S.application Ser. No. 13/204,355, filed Aug. 5, 2011; U.S. applicationSer. No. 12/725,108, filed Mar. 16, 2010; U.S. application Ser. No.12/059,484, filed Mar. 31, 2008; U.S. application Ser. No. 11/935,655,filed Nov. 6, 2007; U.S. application Ser. No. 12/401,478 filed Mar. 10,2009; U.S. application Ser. No. 11/935,655, filed Nov. 6, 2007; and Ser.No. 12/059,484, filed Mar. 31, 2008; U.S. application Ser. No.12/389,946, filed Feb. 20, 2009; and U.S. application Ser. No.12/417,779, filed Apr. 3, 2009, the entire disclosures of each of whichare hereby incorporated by reference.

In a preferred embodiment of the present invention, the generation ofthe reactive moiety, and formation of the bonds between substrates isperformed at ambient temperature. This is particularly important in thecase where the two substrates to be bonded are made of materials havingdiffering coefficients of thermal expansion.

Another object of the present invention is to provide a film compositioncontaining a polymer that undergoes reactive moiety formation underexposure to ionizing radiation, and that contains a down-convertingenergy modulation agent, preferably a phosphor or scintillator material.

The reactive moieties of the present invention can be any reactivemoiety that can be formed by reaction of the reactive composition withionizing radiation, either by direct interaction with the ionizingradiation, or indirectly through energy conversion by an energymodulating agent to generate UV or another energy that generates thereactive moiety. The reactive moieties include, but are not limited to,free radicals, cations, anions, carbenes, nitrenes, etc. For ease ofdiscussion, the following discussion is drawn to generation of freeradicals. However, one of ordinary skill would understand that the sameprocedures can be used to generate the other forms of reactive moieties,which can then interact with compositions to form bonds, thus resultingin bonding of two substrates.

In one embodiment of the invention, peroxides and more suitably organicperoxides (used commercially) can also be used to initiate and createfree-radical polymerization. Some peroxides are initiated by ionizingradiation and others are thermally activated. Examples of suitableperoxides of interest in the present invention include, but are notlimited to:

Once a free-radical initiation takes place, the polymerization ofvarious chemistries can take place. However, in such free radicalinitiated reactions, oxygen inhibition can take place, resulting inincomplete polymerization, and incomplete reaction between chains. Theoxygen dissolved in a given polymeric substance can play the role of achain terminator in a free-radical curing reaction, by way of theformation of a peroxy radical, as shown in the scheme below. Oxygeninhibition is particularly pronounced in systems lacking activehydrogen.

Active hydrogen containing compounds are able to counteract the peroxyradical which leads to further reaction. In various embodiments of thisinvention, oxygen inhibition can be circumvented using varioustechniques. Some active systems to counteract oxygen inhibition includethe presence of hindered/secondary amines (—NH) and allylic (C═C—CH₂-)moieties. Methacrylates contain such allylic hydrogen moities and areless susceptible than acrylates to oxygen inhibition.

Another strategy for counteracting oxygen inhibition is by the inclusionof compounds having multiple active hydrogens. This can particularly beimproved by increasing the functionality from di- to tri- andtetra-functionality. Tetra-functional alcohols provide monomers with sixand eight functionalities.

The compositions of the present invention can be fine-tuned to includethe appropriate concentration of these monomers along with systems withactive hydrogen as well as photo and/or heat active peroxides. Iron, andmore generally, catalytic transition metals result in the formation ofhydroxyl radicals (HO.) superoxide generating systems. Those of ordinaryskill in the art understand that superoxide can reduce ADP-Fe(III) toADP-Fe(II) and, this iron facilitates the apparent production of (HO.).Chelating agents (in the proper proportions) can also alter thereactivity of iron in superoxide-generating systems. It has been shownthat EDTA3 enhances the reactivity of iron toward O₂.— while DETAPAC4drastically slows the O₂.— reaction with iron. The use of catalysts andchelating agents is beneficial to optimizing the desirable free radicalgeneration that leads to the desirable reactions.

In a further preferred embodiment, catalysts can be added for increasingfree radical formation. Suitable catalysts include, but are not limitedto, manganese naphthenate, cobalt naphthenate, and vanadium pentoxidequaternary ammonium salt can be used.

In the case where there is a combination of a UV and a heat activatedperoxide, an initial UV activation can subsequently engender anexothermic reaction which in turn engender the activation of a thermalperoxide. Another simple method of minimizing oxygen inhibition is tocarry out the reaction using an inert atmosphere. The flow of nitrogenand argon on the surface of the materials can be used to limit theoxygen exposure and minimize oxygen induced cure inhibition.

The present invention in various embodiments can utilize a widelyvariety of resins to join to the adherent structures noted above. Theexamples provided here are illustrative of examples rather thaninclusive of the possibilities.

In the present invention, the term polymer includes both homopolymersand copolymers, which collectively can be referred to as (co)polymers.Polymers are molecules with many repetitive units (monomers). The unitscan be the same (identical) in which case this would be a homopolymer.On the other hand the polymer be made of dissimilar units (monomers) inwhich case the polymer would be a copolymer. Covalent bonding isprevalent but there are cases where ionic bonds and hydrogen bonding ispresent, depending on the particular monomers present. Examples ofmonomeric species include, but are not limited to, acrylates,methacrylates, olefins (such as ethylene, propylene, butylene andmixtures thereof), ethers, styrenes, fluoroolefins (such asfluoroethylenes, tetrafluoroethylenes, etc), esters, carbonates,urethanes, vinyl chlorides, vinyl chloride acetates, amides, imides,acetals, methylpentenes, sulfones, acrylics, styrene acrylics,acrylonitrile, etc. Examples of a co-polymer would include, for example,a polymer made from two or more of these species. Furthermore, thedefinition extends to more than two monomeric species includingterpolymers, and a variety of side groups of different structures thanthe blended monomeric species. The term polymer is inclusive of any ofthese variations. Within the present invention, when the presentinvention composition contains a polymer, it is important that thepolymer be able to generate a free radical species by any free radicalgeneration mechanism available to the polymer, including, but notlimited to, hydrogen, atom or group abstraction, chain scission, radicaladdition to unsaturation points in the polymer, etc.

In one embodiment of the present invention, it is desired to initiate achemical reaction using a deeply penetrating and ionizing form of energysuch as X-Ray or e-beam (the initiation energy). The term “X-Raysusceptible polymer” refers to a polymer chemistry that undergoes freeradical formation, such as by atom/group abstraction, chain scission, orother mechanism, under X-Ray; and, as a result will have variouscharacteristics (at least one) changing post exposure to the initiationenergy. The molecular weight of the polymer can be reduced or a sidegroup can be cleaved. Either one of these characteristics is desirablein the present invention. Extended exposure to the initiation energycould result in degradation and therefore there is a low threshold ofenergy (Lower dose for initiation) required to initiate the reaction andan upper energy dose which represents a damage threshold (upper dosecontrol limit).

In one embodiment of the present invention, an example of a “X-Raysusceptible polymer” can include, but is not limited to, aliphaticpolymers. Aliphatic polymers can include alicyclic (no-aromatic rings),alkanes (single bonds), alkenes (unsaturated with double bonds), alkynes(triple bonds) of carbon and hydrogen atoms. One example of an aliphaticpolymer would be polyethylene, or a polyethylene-polypropylenecopolymer.

Peroxides are widely used commercially to initiate and createfree-radical initiation. The reactive free radical species generatedthen reacts with its environment to form chemical bonds. Such methodsare used, for example, to graft maleic anhydride to polyolefins. Ingeneral chain scission can outpace competing reactions. For example, inthe particular case of propylene, chain scission and grafting arecompetitive reactions. However, chain scission outpaces grafting whichcurbs the achievable molecular weight of the grafted resin.

Suitable polyolefins include, but are not limited to polyethylene (PE),polypropylene (PP) and ethyl vinyl acetate (EVA). Polyethylene isconventionally classified according to its density as Very Low DensityPolyethylene (VLDPE), Low Density Polyethylene (LDPE), Linear LowDensity Polyethylene (LLDPE), Medium Density Polyethylene (MDPE), andHigh Density Polyethylene (HDPE).

Examples of propylene polymers include propylene homopolymers andcopolymers of propylene with ethylene or another unsaturated co-monomer.Copolymers also include terpolymers, tetrapolymers, etc. Typically, theunits originating from propylene monomer comprise at least about 70weight percent of the copolymer.

The mechanical and chemical properties of these resins can be tailoredto become suitable for the desired application. The resin type, thecatalyst, molecular weight, molecular weight distribution (MWD),crystallinity, branching and density all play a role in themicrostructure and the behavior of the resin and its performance in theend use application. The choice of these characteristics depending onend use is well within the skill of one of ordinary skill in the art.

As a free radical inducing species for use in the present composition,suitable compounds include, but are not limited to, organic peroxides,azo free-radical initiators, and bicumene. Preferably, the free-radicalinducing species is an organic peroxide. The organic peroxide can beadded via direct injection or via blending with the chemistry of thepolymer. The addition of the organic peroxide is in an amount sufficientto provide a concentration of free radicals sufficient for initiatingreaction at enough sites to effect bonding, preferably from about 0.005weight percent to about 20 weight percent, more preferably from about0.25 weight percent to about 10 weight percent, most preferably fromabout 0.5 weight percent to about 5 weight percent.

In a similar fashion to the technical strategies employed to prohibitoxygen inhibition, the present invention methods can optionally employone or more co-grafting reagents in order to minimize (or curb) chainscission. For this reason reagents containing two or more terminalcarbon-carbon double bonds or triple bonds can be combined withfree-radical generation to mitigate the loss in melt viscosity ofpolypropylene by coupling of polymer chains.

The present invention compositions can optionally further containvarious conventional components that are suitable for the desiredapplication. These can include, but are not limited to, the followingagents: fillers, clays, fire retardant, scorch inhibitors, and blowingagents such as azodicarbonamide.

Activation with X-Ray and UV:

A preferred method of generating free-radicals in the present inventioninclude the use of X-rays, electron-beam and gamma radiation. Thepresent invention can use either X-ray or e-beam both as a source offree radical generation instead of, or in addition to UV light. UVgeneration is performed via the use of energy modulation agents,preferably in the form of particles, that absorb X-ray and convert it toUV. These particles are disposed at the interface where bonding istargeted to take place. The UV light (regardless of its generation) canin turn engender additional free radical generation.

Functional Energy Modulation Agents:

In one aspect of the invention, an energy modulation agent is added tothe chemistry where the energy modulation agent is combined with anorganic peroxide and an organic vehicle. Examples of the energymodulation agent include, but are not limited to: BaFCl:Eu²⁺, BaSO₄⁻:Eu²⁺, LaOBr:Tm³⁺, YTaO₄, YTaO₄:Nb (*), CaWO₄, LaOBr:Tb³⁺, Y₂O₂S:Tb³⁺,ZnS:Ag, (Zn,Cd)S:Ag, Gd₂O₂S:Tb³⁺, La₂O₂S:Tb³⁺. A more comprehensive listis provided in the following table.

Surface Preparation:

Adhesion develops through various factors including mechanicalinterlocking, adsorption, electrostatic, diffusion, weak boundary layer,acid base, chemical (covalent bonding), etc. In general, the greater thesurface irregularities and porosity at a joint area, the greater thejoint strength. The greater the compatibility of the size of theadhesives and the interstices in the adherend, the greater the bondstrength can be. Roughness of the surfaces can increase or decrease thejoint strength.

The factors affecting joint strength include: surface energetics(wetting), intrinsic stresses and stress concentrations, mechanicalresponse of various bulk phases and inter-phases involved, geometricalconsiderations, mode of applying external stresses, mode of fracture orseparation, visco-elastic behavior.

The wetting and the setting of the adhesive bead is important for a goodbond formation. The spreading co-efficient of an adhesive depends on thevarious surfaces and associated surface tensions involved. The surfacetensions are referred to here as the energetic requirements. Thesubstrate (solid), the adhesive (liquid) and the vapor (open air in mostcases) all play a role. Wetting of the surface depends on the surfaceenergy between the solid and the liquid, the liquid to vapor surfacetension and between solid to vapor surface tension. Substrates such asTeflon, PET, Nylon, PE, and PS have low energy. Substrates such asmetals, metal oxides, and ceramics have high energy.

The adhesive chemistry (the liquid in this example) can be tailored toadjust the energetic requirements at the various surfaces. But that isnot sufficient. For example, most RTV silicone resins fulfill theenergetic requirements but give negligible adhesion unless primers areused. Adhesive joints can be made stronger by surface treatments of thesurfaces to be joined. Also inter-phases can be made between theadherend and the adhesive.

For the above considerations (surface energetic requirements and primerstreatments) many surface modification techniques are used to achieve thegoal of strong and durable adhesion at joints. The treatment of polymersurfaces is used for various reasons including one or more of thefollowing list extending to making the polymers more adhesionable,increase their printability, make them more wettable, provide anenclosing layer, improve tribological behavior, potentially prepare themfor metal plating, improve their flame resistance, provide antistaticproperties, control permeation.

Dry surface modification includes, but is not limited to, a surfaceplasma ionized through RF or microwave, flame, UV, UV sensitized, ozone,UV/ozone, X-ray, LASER, electron beam, ion bombardment, and frictionagainst other materials.

Wet surface modification encompasses chemical reactions such asoxidation, sulfonation, ozonation, phosphatization, chromate conversion,amination, grafting, selective etching, deposition of coupling layers(silanes), surfactant adsorption, photochemical compounds, solvent(surface swelling), prevention of diffusion of low molecular weightmaterials to the surface, and others.

In various embodiments of the present invention, the adhesives can beapplied to the substrates using a variety of methods. In the simplestform the adhesive formulations were scooped from the mixing cup using aspatula and deposited on the top surface of one substrate. In othercases the adhesives were placed in syringes and hand pressed through aneedle with an 18 to 22 gauge. In other cases the materials weredispensed through the needle of EDF air piston pump (also using 18 to 22gauge needles). In some cases the substrates had a spacer elementsandwiched between the substrates to keep the materials from beingsqueezed out from between the substrates. The adhesive cure has beendemonstrated for adhesive bead thicknesses from 60 microns to 1000microns.

184 Resin 2100 Weight percent in percent in percent in Ratio of Phosphor% Phosphor Cure Adhesive adhesive adhesive Adhesive % by Weight TypeHardness Around 100 microns 0.94 0.02 0.04 0.75 0.25 CaWO₄ Yes BetweenGlass Slides 0.94 0.02 0.04 0.6 0.4 CaWO₄ Yes 0.88 0.04 0.08 0.75 0.25CaWO₄ Yes Around 250 microns 0.94 0.02 0.04 0.75 0.25 CaWO₄ No BetweenGlass Slides 0.94 0.02 0.04 0.6 0.4 CaWO₄ No 0.88 0.04 0.08 0.75 0.25CaWO₄ Yes

In some cases, this was achieved using a polyimide film, while in othercases the spacer elements were glass beads. The curing of the adhesivethickness of the adhesive beads was successfully demonstrated at 60microns to 250 microns. These thicknesses represent adhesive beads thatwould be compatible with applications such as B-staged films and chip onboard applications. In other cases the adhesive bead was between 500microns to 1000 microns. These thicknesses represent adhesive beads thatwould be compatible with applications such as hermetic sealingapplications.

The control over the rheology and thickness of the adhesive beads wasachieved using filler elements such as AEROSIL and nanoparticles ofdoped Y₂O₃. Gadolinium was found to be the preferred doping elements inthese cases. In order to achieve thicknesses of 500 microns and abovethe adhesive formulations had between 0.5% and 5% of filler.

In some cases, the adhesive bead was applied between 2 polycarbonatesubstrates and kept in this configuration for 24 hours. No-flow ordisplacement was observable. The adhesive bead was therefore made toprovide the end-user with enough work and pot life after dispense and totolerate interruptions of the work in process during manufacturing. Thisis significant because no scarping of the work in process after dispenseis required.

Formulations 1 2 3 4 5 6 Resin 5 5 5 5 — — Resin (shadow cure) — — — — 55 PI (369) 1.3 1.3 1.3 1.3 — — PI (2959) — — — — 0.5 0.5 LaOB:Tm 1.5 2.53.5 2.5 2.5 2.5 Y₂O₃ — — — 0.3 — — AEROSIL 0.2 0.2 0.2 0.2 0.2 0.2CABOSIL — — — — — MEKP — — — 0 0.1 —

The step of X-ray radiation is preferably done in an enclosure thatstops the radiation from leaking to the outside world. The enclosure canbe made of various materials that include heavy metals such as lead. Asingle assembly can be held static or can be moved during cure insidethe enclosure. Such movement could include a rotation movement that canbe achieved using a turn table. Such movement could also include atranslational movement that can be achieved using an external conveyorbelt and an internal conveyor. Both the internal and the externalconveyor belts work in synch to shuttle parts in and out of the X-rayenclosure. The door can open up and close down to shuttle assemblies inand out of the X-ray radiation chamber. When the door is open (or upposition) the X-ray energy is off to adhere to safety measures. TheX-ray enclosure can have automated doors with sensors linked to acontroller. The enclosure can have doors that open up and down toshuttle at least one assembly in and out of the X-ray enclosure forirradiation leading to curing. Furthermore, the assembly to be cured canbe positioned inside a process fixture. The process fixture carries withit the assemblies.

X-ray systems with the capability of programming recipes includingpulsing up to 30 times per sec can be done. A level of control over thekVp as well as amperage can be done to exert control over output poweras well as photon energy which in turns means control over depth ofpenetration.

Additionally, curing time and efficiency can be adjusted as desired byadjustment of various parameters, including, but not limited to,temperature, radiation source intensity, distance of the radiationsource from the adhesive composition to be cured, and photon fluxgenerated by the radiation source.

X-ray delivery head is on one side of the assembly, either above theadhesive bead or below the adhesive bead which can be described (thoughnot exact) that the adhesive bead is generally perpendicular to thedirection of propagation. In some cases the adhesive bead is generallyparallel to the X-ray radiation path. It is recognized however that theX-ray radiation is emitted in a flood beam have multiple directionsaround one predominant direction of propagation.

Ink Jet Cartridges

Ink jet cartridges are typically made of a plastic housing made of athermoplastic moldable resin, such as polyethylene terephthalate (PET),polyethylene, or polysulfone for example, as the base material.Polysulfone describes a family of thermoplastic polymers that havetoughness, mechanical stability and ink resistance.

Typically, a print head made of silicon, has numerous nozzles that areused as ink outlets. The nozzle array on the silicon and the inkreservoirs are connected through a manifold structure having fluidicchannels. The fluidic channels are employed to direct the inks ofdifferent colors from the primary reservoirs to appropriate printheadnozzle arrays.

Multicolor cartridges have a plurality of ink reservoirs, often threeink reservoirs. In such three ink cartridges, each of the reservoirscontains a primary color. These reservoirs need to be isolated from oneanother. The separation between the compartments has to be hermetic toavoid ink mixing between the various compartments. A plastic piece isadhesively bonded to seal the separate reservoirs.

The joint of interest that seals or separates the various reservoirsmust be made to withstand the prolonged contact with inks. Inks happento be aggressive from a chemical stand point. Furthermore, the sealingjoint needs to be able to overcome the mechanical stresses that mayexist over the product's functional life and the pressure differentialthat needs to be regulated between atmospheric pressure and the internalpressure in the reservoir.

The present invention's polymerizable adhesive compositions includingthe adherent surface structures can be used in the formation of inkjetcartridges.

Composites:

The present invention polymerizable adhesive compositions including theadherent surface structures noted above can also be used in theformation of composites, by the adhesion of two or more plies, which arethe fundamental building blocks of layered composites. The compositescan be built by layering the plies, with the plies adhered one to theother using the adhesive composition of the present invention.

The composite is preferably formed by preparation of a prepreg materialformed of the plurality of plies, with each ply placed in the desiredconfiguration with respect to the other plies, and having the curableadhesive composition of the present invention between respective layersof the plies. Once the prepreg is assembled, and the layers aligned asdesired, the curable adhesive can be cured by application of the desiredionizing radiation, such as X-rays, thereby adhering the plies togetherto form the composite.

While many of the above described embodiments use downconvertingparticles that are dispersed throughout the curable adhesivecomposition, many other configurations are available for use with thepresent invention. For example, the downconverting particles can beadhered to a thin film (preferably to both sides of the thin film) whichcan be placed between two surfaces, each of which is coated with thecurable adhesive monomer and photoinitiator formulation. Uponirradiation, the downconverting particles emit energy at the desiredwavelength, activating the photoinitiator, and initiating curing of bothlayers of adhesive, thus bonding each of the surfaces to an oppositeside of the thin film having the downconverting particles. One ofordinary skill, upon reviewing the present invention, would readilyunderstand a wide variety of configurations that could be used to createnovel adhered structures.

In preferred embodiments of the present invention adhesive chemistries,the reaction system is a combination of one or more photoinitiators, oneor more phosphors/energy modulation agents, one or more curable adhesiveprecursors to form an adhesive resin upon curing, and optionally one ormore additives. In these preferred embodiments, the reaction systemcomprises:

(1) one or more photoinitiators selected from the group consisting ofbenzophenone (BP), benzyldimethyl ketal, sulfonium salts, oxime esters,photoacid generators, 1-hydroxy-cyclohexyl-phenyl-ketone,2-hydroxy-2-methyl-1-phenyl-1-propanone,2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methylpropan-1-one,2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone,2,4,6-trimethylbenzoyl-diphenylphosphine oxide,2,4,6-trimethylbenzoyl-diphenyl phosphinate,bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide,[1-(4-phenylsulfanylbenzoyl)heptylideneamino]benzoate,[1-[9-ethyl-6-(2-methylbenzoyl)carbazol-3-yl]ethylideneamino] acetate,2-methyl-1 [4-(methylthio)phenyl]-2-morpholinopropan-1-one,2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one,2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one,iodonium (4-methylphenyl) [4-(2-methylpropyl)phenyl]-hexafluorophosphate(1-), and sulfonium salt cationic initiator;

(2) one or more phosphors/energy modulation agents selected from thegroup consisting of any of the phosphors and energy modulation agentsdescribed above;

(3) one or more curable adhesive resin precursors selected from thegroup consisting of bisphenol A epoxy acrylate, bisphenol A epoxymethacrylate, a chemically modified liquid diglycidyl ether of bisphenolA acrylate, bisphenol F epoxy acrylate, bisphenol F epoxy methacrylate,2.6 functional bisphenol F novolac acrylate, 3.6 functional bisphenol Fnovolac acrylate, cycloaliphatic epoxy acrylate, dimerized fatty acidmodified epoxy acrylate, urethane modified epoxy acrylate, acrylonitrilecontaining liquid elastomer acrylate, neopentyl glycol diglycidyl ethermodified 50% with 82:18 butadiene:acrylonitrile liquid rubber acrylate,liquid epoxy resin adduct of butadiene copolymer with 18% acrylonitrileacrylate, glycidyl ester of neodecanoic acid, epoxidized metaxylylenediamine acrylate, sorbitol polyglycidyl ether acrylate,polyglycerol-3-polyglycidyl ether, propoxylated glycerin triglycidylether, castor oil triglycidyl acrylate, castor oil triglycidylmethacrylate, dipropylene glycol DGE, dicyclopentadiene polyesteracrylate, dicyclopentadiene polyester methacrylate, polyetherpolyurethane acrylate, polyether polyurethane methacrylate, polyesterpolyurethane acrylate, polyester polyurethane methacrylate,polybutadiene acrylate, tripropyleneglycol diacrylate,4-t-butylcyclohexyl acrylate, ethyldiglycol acrylate, andtriethyleneglycol divinyl ether; and

(4) optionally, one or more additives selected from the group consistingof organic acids (methacrylic acid, acrylic acid), amino silanes, epoxysilanes, carboxy silanes, vinyl silanes, mercapto silanes, cobaltabietates, cobalt resinates, cobalt stearates, cobalt naphthenates,cobalt neodecanoates, cobalt boroacylates, peroxides, perbenzoates,copper thiosulfates, nanosilica, precipitated amorphous silica, andcrystalline silica;

and all permutations of components (1)-(4).

These various combinations can be used with or with one or more primers(such as those disclosed and discussed above), depending on thematerials to be bonded together.

In most preferred embodiments, and for best results in the curingreaction, the phosphor, photoinitiator, and curable adhesive resinprecursors are matched such that the active emission of the phosphorupon being treated with x-ray or other high energy sources activates thephotoinitiator to initiate polymerization of the curable adhesive resinprecursor to cure and form the cured adhesive resin.

Having generally described this invention, a further understanding canbe obtained by reference to certain specific examples which are providedherein for purposes of illustration only and are not intended to belimiting unless otherwise specified.

The materials chemistries were prepared by first weighing the keychemical ingredients and mixing these chemical ingredients under heat. Afunctionalized Acrylate resin was obtained from BASF. The resin was madefrom a mixture of 4 commercially available products including Laromer LR9023, Laromer PO 94F, Laromer TPGDA, Laromer LR 9004.

The photoinitiators were also obtained from BASF and consisted ofIRGACURE 369 and IRGACURE 2529. The phosphors were obtained fromPhosphor Technologies. The LaOBr:Tb³⁺ phosphor as well as the YTaO₄ wereused in the preparation of the curing formulations. The third phosphorwas Y₂O₃ doped with Gadolinium (Y₂O₃:Gd). This third phosphor wassynthesized in nano-particle size. It was used both as a phosphor and asa thickening agent.

The temperature that was used during all the mixing steps was 80° C. Thesequence of adding the various chemicals was as follows: 1—resin,2—photoinitiator, 3—phosphor and 4—thickening agent. In one case thethickening agent was the Y₂O₃:Gd. The mixtures stirred every 10 minutesfor one hour to two hours. This ensured the obtainment of a homogenousmixture.

In one case MEKP was added to an adhesive formulation to assess theeffectiveness of X-Ray curing on coupling energy to MEKP and enhancingthe cure kinetics.

It was found that recipe or formulation number 2, 3 and 4 cured fasterthan other formulations. However adhesion was compromised when excessphoto-initiator was used.

For this reason recipe 4 worked best. It cured faster that recipe 2 andhad better adhesion than recipe 3.

Curing of the various formulations was done on PET, glass,polycarbonate, polyimide, polysulfone, a carbon prepreg, a FR4 PCB. Theadhesive bead was sandwiched between two similar substrates and curedwhile in between the substrates. No temperature was increased while inthe x-ray. The temperature was measured using a hand-held IRthermometer. The only time a noticeable temperature increase of up to10° C. was observed is in the case of the formulation containing MEKP.

Formulations 1 2 3 4 5 6 Resin 5 5 5 5 — — Resin (shadow cure) — — — — 55 IRGACURE (369) 1.3 1.3 1.3 1.3 — — IRGACURE (2959) — — — — 0.5 0.5LaOBr:Tb 1.5 2.5 3.5 2.5 2.5 2.5 Y₂O₃ — — — 0.3 — — AEROSIL 0.2 0.2 0.20.2 0.2 0.2 CABOSIL — — — — — MEKP — — — 0 0.1 —

Additional formulations were cured. The elapsed time under X-Ray was 10min, 12.5 min, 15 min, 17.5 min and 20 min. The formulations that weremade using the LaOBr:Tb³ phosphor cured between 10 min and 12.5 min. Theformulations that were made using the phosphor YTaO₄ cured between 12.5min and 15 min. The formulations using the third phosphor was Y₂O₃ dopedwith Gadolinium (Y₂O₃:Gd) cured in 17.5 minutes. However when theLaOBr:Tb³⁺ mixed with Y₂O₃:Gd were added to the adhesive formulations,the cure was accomplished in 10 min.

Formulations 1 2 3 4 5 6 Resin 1 6 6 6 6 6 6 Resin 2 (shadow Cure) 0 0 00 0 0 PI (369) 0.6 0.6 0.6 0.6 0.6 0.6 LaOBr:Tb 1.5 1.5 Y₂O₃-Ian 1.5 1.5YTaO₄ 1.5 1.5 AEROSIL 0.3 0.3 0.3 0.3 0.3 0.3

Besides the objects noted above, the bonding and curing andcross-linking processes described herein can be applied in theproduction of a variety of products adhering pieces together (havingsimilar or dissimilar properties) to form final or intermediate productsin a production process. Such products include, but are not limited to,athletic equipment, sporting equipment, industrial equipment,construction equipment, office equipment, baseballs, basketballs,volleyballs, golf balls, footballs, soccer balls, bowling pins, bowlingballs, golf clubs, laminated furniture items, car panels, car interiorproducts, tires, plastic covers, plastic containers, consumer and foodpackaging products, medical packaging products, etc.

PREFERRED EMBODIMENTS OF THE INVENTION Embodiment 1

A method of adhesive bonding, comprising:

a) providing an adherent structure including one or more rubbercompounds on a surface of an element to be bonded;

b) placing a polymerizable adhesive composition, including at least onephotoinitiator and at least one energy converting material, in contactwith the adherent structure and two or more components to be bonded toform an assembly;

c) irradiating the assembly with radiation at a first wavelength,capable of conversion by the at least one energy converting material toa second wavelength capable of activating the at least onephotoinitiator to produce from the polymerizable adhesive composition acured adhesive composition; and

d) adhesively joining the two or more components by way of the adherentstructure and the cured adhesive composition.

Embodiment 2

The method of embodiment 1, wherein said at least one energy convertingmaterial is a downconverting material.

Embodiment 3

The method of embodiment 2, wherein said downconverting materialcomprises inorganic particulates selected from the group consisting of:metal oxides; metal sulfides; doped metal oxides; and mixed metalchalcogenides.

Embodiment 4

The method of embodiment 2, wherein said downconverting materialcomprises at least one of Y₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃,La₃, LaF₃, LaCl₃, La₂O₃, TiO₂, LuPO₄, YVO₄, YbF₃, YF₃, Na-doped YbF₃,ZnS; ZnSe; MgS; CaS; ZnSe_(x)S_(y); ZnSe_(x)S_(y):Cu, Ag, Ce, Tb; andalkali lead silicate including compositions of SiO₂, B₂O₃, Na₂O, K₂O,PbO, MgO, or Ag, and combinations or alloys or layers thereof.

Embodiment 5

The method of embodiment 4, wherein the downconverting materialcomprises a dopant including at least one of Er, Eu, Yb, Tm, Nd, Mn Tb,Ce, Y, U, Pr, La, Gd and other rare-earth species or a combinationthereof.

Embodiment 6

The method of embodiment 2, wherein the downconverting materialcomprises at least one of CaS, ZnSeS, and iron sulfate.

Embodiment 7

The method of embodiment 2, wherein said first wavelength of radiationis at least one of X-rays, electron beams, and UV light.

Embodiment 8

The method of embodiment 1, wherein said at least one energy convertingmaterial comprises an upconverting material.

Embodiment 9

The method of embodiment 8, wherein said first wavelength of radiationis near infrared.

Embodiment 10

The method of embodiment 8, wherein said upconverting material comprisesat least one of Y₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃, LaF₃,LaCl₃, La₂O₃, TiO₂, LuPO₄, YVO₄, YbF₃, YF₃, Na-doped YbF₃, or SiO₂ oralloys or layers thereof.

Embodiment 11

The method of embodiment 1, wherein said polymerizable adhesivecomposition comprises a monomer forming a thermoset resin.

Embodiment 12

The method of embodiment 1, further comprising adding a peroxide to thepolymerizable adhesive composition.

Embodiment 13

The method of embodiment 1, wherein said at least one photoinitiator isselected from the group consisting of: benzoin ethers, benzil ketals,α-dialkoxyacetophenones, α-aminoalkylphenones, acylphosphine oxides,benzophenones/amines, thioxanthones/amines, and titanocenes.

Embodiment 14

The method of embodiment 1, wherein said polymerizable adhesivecomposition comprises inorganic particulates selected from the groupconsisting of: metals and metal alloys, ceramics and dielectrics, andmetal-coated polymers.

Embodiment 15

The method of embodiment 14, wherein said polymerizable adhesivecomposition comprises an organic component selected from the groupconsisting of: solvents, viscosity modifiers, surfactants, dispersants,and plasticizers.

Embodiment 16

The method of embodiment 1, wherein providing an adherent structurecomprises:

providing a solution containing natural or synthetic rubber compounds onsaid surface of the element to be bonded;

removing said solvent;

polymerizing said rubber compounds.

Embodiment 17

The method of embodiment 16, wherein the polymerization comprisesexposing the rubber compounds to at least one of x-rays, e-beam, or UVflux.

Embodiment 18

The method of embodiment 17, wherein the exposing comprises breakingdouble bonds in the rubber compounds followed by bonding of the rubbercompounds to the surface of the element to be bonded.

Embodiment 19

The method of embodiment 16, wherein the solution is provided with aconcentration of the natural or synthetic rubber compounds between 33%and 45%.

Embodiment 20

The method of embodiment 1, wherein the surface of the element to bebonded comprises a low energy material having a surface energy of lessthan 50 mJ/m².

Embodiment 21

The method of embodiment 1, wherein the surface of the element to bebonded comprises a low energy material having a surface energy of lessthan 40 mJ/m².

Embodiment 22

The method of embodiment 1, wherein the surface of the element to bebonded comprises a low energy material having a surface energy of lessthan 30 mJ/m².

Embodiment 23

The method of embodiment 1, wherein the surface of the element to bebonded comprises at least one of a polytetrafluoroethylene, apoly(perfluoroalkylacrylate), a polystyrene, a polyacrylate, apoly(methyl methacrylate), a poly(dimethylsiloxane), a polyethylene, apolychlorotrifluoroethylene, a polypropylene, a polyvinyl chloride, apolyvinyl fluoride, a polyvinylidenedichloride, apolyvinylidenedifluoride, a polyacrylamide, polyethylene terephthalate,a poly(6-aminocoproicacid), and a poly(l 1-aminoundecaroicacid).

Embodiment 24

The method of embodiment 1, wherein the surface of the element to bebonded comprises at least one of a silicone and a poly (dimethylsiloxane).

Embodiment 25

The method of embodiment 1, wherein providing an adherent structurecomprises modifying said surface of the element to increase a surfaceenergy thereof.

Embodiment 26

The method of embodiment 25, wherein modifying comprises exposing saidsurface to a plasma treatment.

Embodiment 27

The method of embodiment 25, wherein modifying comprises exposing saidsurface to a plasma treatment at atmospheric pressure conditions.

Embodiment 28

The method of embodiment 25, wherein modifying comprises exposing saidsurface to a chemical etchant.

Embodiment 29

The method of embodiment 1, wherein providing an adherent structurecomprises applying a primer to said surface of the element to be bonded.

Embodiment 30

The method of embodiment 29, wherein the primer comprises atwo-component urethane-based primer.

Embodiment 31

The method of embodiment 30, wherein the two-component urethane-basedprimer comprises a moisture activated primer.

Embodiment 32

The method of embodiment 1, wherein said at least one energy convertingmaterial comprises an organic phosphor.

Embodiment 33

The method of embodiment 32, wherein the at least one photoinitiator isconfigured to be activated by emitted light from one or more of organicphosphors.

Embodiment 34

The method of embodiment 32, wherein the organic phosphor comprises atleast one of anthracene, sulfoflavine, fluorescein, eosin,polyvinyltoluene, styrene, fluors, and rhodamine.

Embodiment 35

The method of embodiment 32, wherein the organic phosphor is linked tothe at least one photoinitiator.

Embodiment 36

A curable polymer system comprising:

an adherent structure attached to a low energy surface of an element tobe bonded, said surface having a surface energy less than 50 mJ/m²;

at least one polymerizable adhesive composition for adhesive attachmentto the adherent structure;

at least one photoinitiator responsive to a selected wavelength oflight; and

at least one energy converting material selected to emit said wavelengthof light when exposed to an imparted radiation.

Embodiment 37

The system of embodiment 36, wherein said at least one energy convertingmaterial is a downconverting material.

Embodiment 38

The system of embodiment 37, wherein said downconverting materialcomprises inorganic particulates selected from the group consisting of:metal oxides; metal sulfides; doped metal oxides; and mixed metalchalcogenides.

Embodiment 39

The system of embodiment 37, wherein said downconverting materialcomprises at least one of Y₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃,LaF₃, LaCl₃, La₂O₃, TiO₂, LuPO₄, YVO₄, YbF₃, YF₃, Na-doped YbF₃, ZnS;ZnSe; MgS; CaS; ZnSe_(x)S_(y); ZnSe_(x)S_(y):Cu, Ag, Ce, Tb; and alkalilead silicate including compositions of SiO₂, B₂O₃, Na₂O, K₂O, PbO, MgO,or Ag, and combinations or alloys or layers thereof.

Embodiment 40

The system of embodiment 39, wherein the downconverting materialcomprises a dopant including at least one of Er, Eu, Yb, Tm, Nd, Mn Tb,Ce, Y, U, Pr, La, Gd and other rare-earth species or a combinationthereof.

Embodiment 41

The system of embodiment 37, wherein the downconverting materialcomprises at least one of CaS, ZnSeS, and iron sulfate.

Embodiment 42

The system of embodiment 36, wherein said at least one energy convertingmaterial comprises an upconverting material.

Embodiment 43

The system of embodiment 42, wherein said upconverting materialcomprises at least one of Y₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃,LaF₃, LaCl₃, La₂O₃, TiO₂, LuPO₄, YVO₄, YbF₃, YF₃, Na-doped YbF₃, or SiO₂or alloys or layers thereof.

Embodiment 44

The system of embodiment 36, wherein said polymerizable adhesivecomposition comprises a monomer forming a thermoset resin.

Embodiment 45

The system of embodiment 44, further comprising a peroxide included inthe polymerizable adhesive composition.

Embodiment 46

The system of embodiment 36, wherein said at least one photoinitiator isselected from the group consisting of: benzoin ethers, benzil ketals,α-dialkoxyacetophenones, α-aminoalkylphenones, acylphosphine oxides,benzophenones/amines, thioxanthones/amines, and titanocenes.

Embodiment 47

The system of embodiment 36, wherein said polymerizable adhesivecomposition further comprises inorganic particulates selected from thegroup consisting of: metals and metal alloys, ceramics and dielectrics,and metal-coated polymers.

Embodiment 48

The system of embodiment 46, wherein said polymerizable adhesivecomposition further comprises an organic component selected from thegroup consisting of: solvents, viscosity modifiers, surfactants,dispersants, and plasticizers.

Embodiment 49

The system of embodiment 36, wherein the adherent structure comprises:

a polymerized natural or synthetic rubber compound.

Embodiment 50

The system of embodiment 36, wherein the surface of the element to bebonded comprises a low energy material having a surface energy of lessthan 50 mJ/m².

Embodiment 51

The system of embodiment 36, wherein the surface of the element to bebonded comprises a low energy material having a surface energy of lessthan 40 mJ/m².

Embodiment 52

The system of embodiment 36, wherein the surface of the element to bebonded comprises a low energy material having a surface energy of lessthan 30 mJ/m².

Embodiment 53

The system of embodiment 36, wherein the surface of the element to bebonded comprises at least one of a polytetrafluoroethylene, apoly(perfluoroalkylacrylate), a polystyrene, a polyacrylate, apoly(methyl methacrylate), a poly(dimethylsiloxane), a polyethylene, apolychlorotrifluoroethylene, a polypropylene, a polyvinyl chloride, apolyvinyl fluoride, a polyvinylidenedichloride, apolyvinylidenedifluoride, a polyacrylamide, a polyethyleneterephthalate, a poly(6-aminocoproicacid), and apoly(11-aminoundecaroicacid).

Embodiment 54

The system of embodiment 36, wherein the surface of the element to bebonded comprises at least one of a silicone and a poly (dimethylsiloxane).

Embodiment 55

The system of embodiment 36, further comprising a primer for applicationto said surface of the element to be bonded.

Embodiment 56

The system of embodiment 55, wherein the primer comprises atwo-component urethane-based primer.

Embodiment 57

The system of embodiment 55, wherein the two-component urethane-basedprimer comprises a moisture activated primer.

Embodiment 58

The system of embodiment 36, wherein said at least one energy convertingmaterial comprises an organic phosphor.

Embodiment 59

The system of embodiment 58, wherein the at least one photoinitiator isconfigured to be activated by emitted light from one or more of organicphosphors.

Embodiment 60

The system of embodiment 58, wherein the organic phosphor comprises atleast one of include anthracene, sulfoflavine, fluorescein, eosin,polyvinyltoluene, styrene, fluors, and rhodamine.

Embodiment 61

The system of embodiment 58, wherein the organic phosphor is linked tothe at least one photoinitiator.

Embodiment 62

An inkjet cartridge, comprising a printhead and a cartridge body,wherein the printhead and cartridge body are held together by the curedadhesive composition of embodiment 36.

Embodiment 63

A wafer to wafer bonded assembly, comprising a plurality ofsemiconductor wafers bonded together the cured adhesive composition ofembodiment 36.

Embodiment 64

An encapsulated semiconductor component, comprising a semiconductorassembly having the cured adhesive composition of embodiment 36.

Embodiment 65

An integrated circuit assembly comprising a plurality of electricallyconnected material layers, wherein the plurality of electricallyconnected material layers are held together by the cured adhesivecomposition of embodiment 36.

Embodiment 66

An adhesive transfer member comprising:

a release substrate;

one or more rubber compounds disposed on a surface of the releaseelement; and

an energy converting material intermixed with said one or rubbercompounds in the surface of the release element.

Embodiment 67

The member of embodiment 66, wherein said energy converting material isa downconverting material.

Embodiment 68

The member of embodiment 67, wherein said downconverting materialcomprises inorganic particulates selected from the group consisting of:metal oxides; metal sulfides; doped metal oxides; and mixed metalchalcogenides.

Embodiment 69

The member of embodiment 67, wherein said downconverting materialcomprises at least one of Y₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃,LaF₃, LaCl₃, La₂O₃, TiO₂, LuPO₄, YVO₄, YbF₃, YF₃, Na-doped YbF₃, ZnS;ZnSe; MgS; CaS; ZnSe_(x)S_(y); ZnSe_(x)S_(y):Cu, Ag, Ce, Tb; and alkalilead silicate including compositions of SiO₂, B₂O₃, Na₂O, K₂O, PbO, MgO,or Ag, and combinations or alloys or layers thereof.

Embodiment 70

The member of embodiment 67, wherein the downconverting materialcomprises a dopant including at least one of Er, Eu, Yb, Tm, Nd, Mn Tb,Ce, Y, U, Pr, La, Gd and other rare-earth species or a combinationthereof.

Embodiment 71

The member of embodiment 67, wherein the downconverting materialcomprises at least one of CaS, ZnSeS, and iron sulfate.

Embodiment 72

The member of embodiment 66, wherein said at least one energy convertingmaterial comprises an upconverting material.

Embodiment 73

The member of embodiment 72, wherein said upconverting materialcomprises at least one of Y₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃,LaF₃, LaCl₃, La₂O₃, TiO₂, LuPO₄, YVO₄, YbF₃, YF₃, Na-doped YbF₃, or SiO₂or alloys or layers thereof.

Embodiment 74

The member of embodiment 66, wherein said release substrate comprisesmylar.

Embodiment 75

The member of embodiment 66, further comprising a peroxide added to theone or more rubber compounds.

Embodiment 76

An article comprising:

a first member;

a second member;

adherent structure including one or more rubber compounds attached to atleast one of the first and second member; and

a polymerizable adhesive composition joining the first member to thesecond member and including at least one photoinitiator and at least oneenergy converting material.

Embodiment 77

The article of embodiment 76, wherein the article includes at least oneof a textile, a clothing article, a construction article, asemiconductor device, a plastic article, and a metal article.

Embodiment 78

The article of embodiment 76, wherein the at least one energy convertingmaterial comprises a downconverting material.

Embodiment 79

The article of embodiment 78, wherein the downconverting materialcomprises inorganic particulates selected from the group consisting of:metal oxides; metal sulfides; doped metal oxides; and mixed metalchalcogenides.

Embodiment 80

The article of embodiment 78, wherein the downconverting materialcomprises at least one of Y₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃,LaF₃, LaCl₃, La₂O₃, TiO₂, LuPO₄, YVO₄, YbF₃, YF₃, Na-doped YbF₃, ZnS;ZnSe; MgS; CaS; ZnSe_(x)S_(y); ZnSe_(x)S_(y):Cu, Ag, Ce, Tb; and alkalilead silicate including compositions of SiO₂, B₂O₃, Na₂O, K₂O, PbO, MgO,or Ag, and combinations or alloys or layers thereof.

Embodiment 81

The article of embodiment 78, wherein the downconverting materialcomprises a dopant including at least one of Er, Eu, Yb, Tm, Nd, Mn Tb,Ce, Y, U, Pr, La, Gd and other rare-earth species or a combinationthereof.

Embodiment 82

The article of embodiment 78, wherein the downconverting materialcomprises at least one of CaS, ZnSeS, and iron sulfate.

Embodiment 83

The article of embodiment 76, wherein the at least one energy convertingmaterial comprises an upconverting material.

Embodiment 84

The article of embodiment 83, wherein the upconverting materialcomprises at least one of Y₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃,LaF₃, LaCl₃, La₂O₃, TiO₂, LuPO₄, YVO₄, YbF₃, YF₃, Na-doped YbF₃, or SiO₂or alloys or layers thereof.

Embodiment 85

The article of embodiment 76, wherein the at least one photoinitiator isselected from the group consisting of: benzoin ethers, benzil ketals,α-dialkoxyacetophenones, α-aminoalkylphenones, acylphosphine oxides,benzophenones/amines, thioxanthones/amines, and titanocenes.

Embodiment 86

The article of embodiment 76, wherein the polymerizable adhesivecomposition comprises inorganic particulates selected from the groupconsisting of: metals and metal alloys, ceramics and dielectrics, andmetal-coated polymers.

Embodiment 87

The article of embodiment 76, wherein the polymerizable adhesivecomposition comprises an organic component selected from the groupconsisting of: solvents, viscosity modifiers, surfactants, dispersants,and plasticizers.

Embodiment 88

The article of embodiment 76, wherein the adherent structure comprises anatural or synthetic rubber compound.

Embodiment 89

The article of embodiment 76, wherein at least one of the first andsecond members comprises at least one of a polytetrafluoroethylene, apoly(perfluoroalkylacrylate), a polystyrene, a polyacrylate, apoly(methyl methacrylate), a poly(dimethylsiloxane), a polyethylene, apolychlorotrifluoroethylene, a polypropylene, a polyvinyl chloride, apolyvinyl fluoride, a polyvinylidenedichloride, apolyvinylidenedifluoride, a polyacrylamide, a polyethyleneterephthalate, a poly(6-aminocoproicacid), and apoly(11-aminoundecaroicacid).

Embodiment 90

The article of embodiment 76, wherein at least one of the first andsecond members comprises at least one of a silicone and a poly (dimethylsiloxane).

Embodiment 91

The article of embodiment 76, further comprising a primer disposed on atleast one of the first and second members.

Embodiment 92

The article of embodiment 76, wherein the primer comprises atwo-component urethane-based primer.

Embodiment 93

The article of embodiment 92, wherein the two-component urethane-basedprimer comprises a moisture activated primer.

Embodiment 94

The article of embodiment 92, wherein the at least one energy convertingmaterial comprises an organic phosphor.

Embodiment 95

The article of embodiment 94, wherein organic phosphor comprises atleast one of anthracene, sulfoflavine, fluorescein, eosin,polyvinyltoluene, styrene, fluors, and rhodamine.

Embodiment 96

The article of embodiment 95, wherein the organic phosphor is linked tothe at least one photoinitiator.

Embodiment 97

A method of adhesive bonding comprising:

a) providing a polymerizable adhesive composition on a surface of anelement to be bonded to form an assembly;

b) irradiating the assembly with radiation at a first wavelength capableof vulcanization of bonds in the polymerizable adhesive composition byactivation of sulfur-containing compound with at least one-ray, e-beam,visible, or infrared light to thereby generate ultraviolet light in thepolymerizable adhesive composition; and

c) adhesively joining two or more components together by way of thepolymerizable adhesive composition.

Embodiment 98

The method of embodiment 97, wherein irradiating comprises severingbonds in the adhesive composition to promote said vulcanization.

Embodiment 99

The method of embodiment 97, wherein irradiating comprises irradiatingat least one energy converting material in the polymerizable adhesivecomposition.

Embodiment 100

The method of embodiment 99, wherein said at least one energy convertingmaterial is a downconverting material.

Embodiment 101

The method of embodiment 100, wherein said downconverting materialcomprises inorganic particulates selected from the group consisting of:metal oxides; metal sulfides; doped metal oxides; and mixed metalchalcogenides.

Embodiment 102

The method of embodiment 100, wherein said downconverting materialcomprises at least one of Y₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃,LaF₃, LaCl₃, La₂O₃, TiO₂, LuPO₄, YVO₄, YbF₃, YF₃, Na-doped YbF₃, ZnS;ZnSe; MgS; CaS; ZnSe_(x)S_(y); ZnSe_(x)S_(y):Cu, Ag, Ce, Tb; and alkalilead silicate including compositions of SiO₂, B₂O₃, Na₂O, K₂O, PbO, MgO,or Ag, and combinations or alloys or layers thereof.

Embodiment 103

The method of embodiment 100, wherein the downconverting materialcomprises a dopant including at least one of Er, Eu, Yb, Tm, Nd, Mn Tb,Ce, Y, U, Pr, La, Gd and other rare-earth species or a combinationthereof.

Embodiment 104

The method of embodiment 97, wherein the sulfur-containing compoundcomprises at least one of CaS, ZnSeS, and iron sulfate.

Embodiment 105

The method of embodiment 99, wherein said at least one energy convertingmaterial further comprises an upconverting material.

Embodiment 106

The method of embodiment 105, wherein said upconverting materialcomprises at least one of Y₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃,LaF₃, LaCl₃, La₂O₃, TiO₂, LuPO₄, YVO₄, YbF₃, YF₃, Na-doped YbF₃, or SiO₂or alloys or layers thereof.

Embodiment 107

The method of embodiment 97, wherein said polymerizable adhesivecomposition includes an organic vehicle comprising in part a monomerforming a thermoset resin.

Embodiment 108

The method of embodiment 107, wherein said thermoset resin is selectedfrom the group consisting of: acrylics, phenolics, urethanes, epoxies,styrenes, and silicones.

Embodiment 109

The method of embodiment 97, wherein said polymerizable adhesivecomposition includes at least one photoinitiator selected from the groupconsisting of: benzoin ethers, benzil ketals, α-dialkoxyacetophenones,α-aminoalkylphenones, acylphosphine oxides, benzophenones/amines,thioxanthones/amines, and titanocenes.

Embodiment 110

The method of embodiment 109, wherein said polymerizable adhesivecomposition further comprises inorganic particulates selected from thegroup consisting of: metals and metal alloys, ceramics and dielectrics,and metal-coated polymers.

Embodiment 111

The method of embodiment 97, wherein said polymerizable adhesivecomposition further comprises an organic component selected from thegroup consisting of: solvents, viscosity modifiers, surfactants,dispersants, and plasticizers.

Embodiment 112

The method of embodiment 97, wherein providing a polymerizable adhesivecomposition comprises:

providing a solution containing natural or synthetic rubber compounds onsaid surface of the element to be bonded;

removing said solvent;

polymerizing said rubber compounds.

Embodiment 113

The method of embodiment 112, wherein the polymerization comprisesexposing the rubber compounds to at least one of x-rays, e-beam, or UVflux.

Embodiment 114

The method of embodiment 113, wherein the exposing produces breakage ofdouble bonds in the rubber compounds followed by bonding of the rubbercompounds to the surface of the element to be bonded.

Embodiment 115

The method of embodiment 97, wherein the surface of the element to bebonded comprises at least one of a polytetrafluoroethylene, apoly(perfluoroalkylacrylate), a polystyrene, a polyacrylate, apoly(methyl methacrylate), a poly(dimethylsiloxane), a polyethylene, apolychlorotrifluoroethylene, a polypropylene, a polyvinyl chloride, apolyvinyl fluoride, a polyvinylidenedichloride, apolyvinylidenedifluoride, a polyacrylamide, a polyethyleneterephthalate, a poly(6-aminocoproicacid), and apoly(1-aminoundecaroicacid).

Embodiment 116

The method of embodiment 97, wherein the surface of the element to bebonded comprises at least one of a silicone and a poly (dimethylsiloxane).

Embodiment 117

A curable polymer comprising:

a polymerizable adhesive composition; and

said polymerizable adhesive composition including a sulfur-containingcompound, and capable of being cured by vulcanization of bonds in thepolymerizable adhesive composition upon exposure to at least one ofx-rays, e-beam, or IR flux.

Embodiment 118

The polymer of embodiment 117, further comprising an energy convertingmaterial comprising at least one of a downconverting material and an upconverting material.

Embodiment 119

The polymer of embodiment 118, wherein the energy converting materialcomprises a downconverting material.

Embodiment 120

The polymer of embodiment 119, wherein said downconverting materialcomprises inorganic particulates selected from the group consisting of:metal oxides; metal sulfides; doped metal oxides; and mixed metalchalcogenides.

Embodiment 121

The polymer of embodiment 119, wherein said downconverting materialcomprises at least one of Y₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃,LaF₃, LaCl₃, La₂O₃, TiO₂, LuPO₄, YVO₄, YbF₃, YF₃, Na-doped YbF₃, ZnS;ZnSe; MgS; CaS; ZnSe_(x)S_(y); ZnSe_(x)S_(y):Cu, Ag, Ce, Tb; and alkalilead silicate including compositions of SiO₂, B₂O₃, Na₂O, K₂O, PbO, MgO,or Ag, and combinations or alloys or layers thereof.

Embodiment 122

The polymer of embodiment 121, wherein the downconverting materialcomprises a dopant including at least one of Er, Eu, Yb, Tm, Nd, Mn Tb,Ce, Y, U, Pr, La, Gd and other rare-earth species or a combinationthereof.

Embodiment 123

The polymer of embodiment 117, wherein the sulfur-containing compoundcomprises at least one of CaS, ZnSeS, and iron sulfate.

Embodiment 124

The polymer of embodiment 118, wherein the energy converting materialcomprises an upconverting material.

Embodiment 125

The polymer of embodiment 124, wherein said upconverting materialcomprises at least one of Y₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃,LaF₃, LaCl₃, La₂O₃, TiO₂, LuPO₄, YVO₄, YbF₃, YF₃, Na-doped YbF₃, or SiO₂or alloys or layers thereof.

Embodiment 126

The polymer of embodiment 117, further comprising a surface to be bondedcomprising at least one of a polytetrafluoroethylene, apoly(perfluoroalkylacrylate), a polystyrene, a polyacrylate, apoly(methyl methacrylate), a poly(dimethylsiloxane), a polyethylene, apolychlorotrifluoroethylene, a polypropylene, a polyvinyl chloride, apolyvinyl fluoride, a polyvinylidenedichloride, apolyvinylidenedifluoride, a polyacrylamide, a polyethyleneterephthalate, a poly(6-aminocoproicacid), and apoly(11-aminoundecaroicacid).

Embodiment 127

The polymer of embodiment 117, further comprising a surface to be bondedcomprising at least one of a silicone and a poly (dimethyl siloxane).

Embodiment 128

The polymer of embodiment 117, further comprising a primer forapplication to said surface of the element to be bonded.

Embodiment 129

The polymer of embodiment 128, wherein the primer comprises atwo-component urethane-based primer.

Embodiment 130

The polymer of embodiment 129, wherein the two-component urethane-basedprimer comprises a moisture activated primer.

Embodiment 131

The polymer of embodiment 118, wherein said at least one energyconverting material comprises an organic phosphor.

Embodiment 132

The polymer of embodiment 131, wherein the organic phosphor comprises atleast one of include anthracene, sulfoflavine, fluorescein, eosin,polyvinyltoluene, styrene, fluors, and rhodamine.

Embodiment 133

A method of adhesive bonding, comprising:

a) providing an adherent structure including one or more rubbercompounds on respective surfaces to be adhesively joined;

b) contacting the surfaces together; and

c) irradiating the adherent structure with radiation capable of directlyor indirectly cross-linking the one or more rubber compounds.

Embodiment 134

The method of embodiment 133, wherein irradiating comprises irradiatingwith at least one of x-rays, e-beam, or infrared radiation.

Embodiment 135

The method of embodiment 133, wherein irradiating comprises irradiatingan energy converting material comprising at least one of adownconverting material and an up converting material.

Embodiment 136

The method of embodiment 135, wherein the energy converting materialcomprises a downconverting material.

Embodiment 137

The method of embodiment 135, wherein said downconverting materialcomprises inorganic particulates selected from the group consisting of:metal oxides; metal sulfides; doped metal oxides; and mixed metalchalcogenides.

Embodiment 138

The method of embodiment 135, wherein said downconverting materialcomprises at least one of Y₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃,LaF₃, LaCl₃, La₂O₃, TiO₂, LuPO₄, YVO₄, YbF₃, YF₃, Na-doped YbF₃, ZnS;ZnSe; MgS; CaS; ZnSe_(x)S_(y); ZnSe_(x)S_(y):Cu, Ag, Ce, Tb; and alkalilead silicate including compositions of SiO₂, B₂O₃, Na₂O, K₂O, PbO, MgO,or Ag, and combinations or alloys or layers thereof.

Embodiment 139

The method of embodiment 135, wherein the downconverting materialcomprises a dopant including at least one of Er, Eu, Yb, Tm, Nd, Mn Tb,Ce, Y, U, Pr, La, Gd and other rare-earth species or a combinationthereof.

Embodiment 140

The method of embodiment 133, wherein irradiating comprises irradiatinga sulfur-containing compound.

Embodiment 141

The method of embodiment 140, wherein the sulfur-containing compoundcomprises at least one of CaS, ZnSeS, and iron sulfate.

Embodiment 142

The method of embodiment 135, wherein the energy converting materialcomprises an upconverting material.

Embodiment 143

The method of embodiment 142, wherein said upconverting materialcomprises at least one of Y₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃,LaF₃, LaCl₃, La₂O₃, TiO₂, LuPO₄, YVO₄, YbF₃, YF₃, Na-doped YbF₃, or SiO₂or alloys or layers thereof.

Embodiment 144

The method of embodiment 133, wherein at least one of the respectivesurfaces comprises at least one of a polytetrafluoroethylene, apoly(perfluoroalkylacrylate), a polystyrene, a polyacrylate, apoly(methyl methacrylate), a poly(dimethylsiloxane), a polyethylene, apolychlorotrifluoroethylene, a polypropylene, a polyvinyl chloride, apolyvinyl fluoride, a polyvinylidenedichloride, apolyvinylidenedifluoride, a polyacrylamide, a polyethyleneterephthalate, a poly(6-aminocoproicacid), and a poly(l1-aminoundecaroicacid).

Embodiment 145

The method of embodiment 133, wherein at least one of the respectivesurfaces comprises at least one of a silicone and a poly (dimethylsiloxane).

Embodiment 146

The method of embodiment 135, wherein the energy converting materialcomprises an organic phosphor.

Embodiment 147

The method of embodiment 146, wherein the organic phosphor comprises atleast one of anthracene, sulfoflavine, fluorescein, eosin,polyvinyltoluene, styrene, fluors, and rhodamine.

Embodiment 148

The method of embodiment 133, wherein contacting the surfaces togethercomprises:

applying the one or more rubber compounds to a release substrate;

contacting the release substrate to one of the respective surfaces; and

removing the release substrate and leaving the one or more rubbercompounds disposed on said one of the respective surfaces.

Embodiment 149

The method of embodiment 148, wherein the release substrate comprisesmylar.

Embodiment 150

The method of embodiment 148, wherein the release substrate is siliconecoated.

Embodiment 151

The method of embodiment 133, wherein contacting the surfaces togethercomprises:

applying the one or more rubber compounds to a release substrate byimmersing the release substrate in a solution of the one or more rubbercompounds.

Additional modifications and variations of the present invention arepossible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described herein.

The invention claimed is:
 1. A method of adhesive bonding comprising: a)providing a polymerizable adhesive composition on a surface of anelement to be bonded to form an assembly, wherein said polymerizableadhesive composition includes an organic vehicle comprising in part amonomer forming a thermoset resin; b) irradiating the assembly withradiation at a first wavelength capable of vulcanization of bonds in thepolymerizable adhesive composition by activation of sulfur-containingcompound with at least one X-ray, e-beam, visible, or infrared light tothereby generate ultraviolet light in the polymerizable adhesivecomposition, wherein the sulfur-containing compound comprises at leastone member selected from the group consisting of CaS, ZnSeS, and ironsulfate; and c) adhesively joining two or more components together byway of the polymerizable adhesive composition.
 2. The method of claim 1,wherein irradiating comprises severing bonds in the adhesive compositionto promote said vulcanization.
 3. The method of claim 1, wherein saidthermoset resin is selected from the group consisting of acrylics,phenolics, urethanes, epoxies, styrenes, and silicones.
 4. The method ofclaim 1, wherein said polymerizable adhesive composition includes atleast one photoinitiator selected from the group consisting of benzoinethers, benzil ketals, α-dialkoxyacetophenones, α-aminoalkylphenones,acylphosphine oxides, benzophenones/amines, thioxanthones/amines, andtitanocenes.
 5. The method of claim 1, wherein said polymerizableadhesive composition further comprises inorganic particulates selectedfrom the group consisting of metals and metal alloys, ceramics anddielectrics, and metal-coated polymers.
 6. The method of claim 1,wherein said polymerizable adhesive composition further comprises anorganic component selected from the group consisting of solvents,viscosity modifiers, surfactants, dispersants, and plasticizers.
 7. Themethod of claim 1, wherein the surface of the element to be bondedcomprises at least one member selected from the group consisting of apolytetrafluoroethylene, a poly(perfluoroalkylacrylate), a polystyrene,a polyacrylate, a poly(methyl methacrylate), a poly(dimethylsiloxane), apolyethylene, a polychlorotrifluoroethylene, a polypropylene, apolyvinyl chloride, a polyvinyl fluoride, a polyvinylidenedichloride, apolyvinylidenedifluoride, a polyacrylamide, a polyethyleneterephthalate, a poly(6-aminocoproicacid), and apoly(11-aminoundecaroicacid).
 8. The method of claim 1, wherein thesurface of the element to be bonded comprises at least one memberselected from the group consisting of a silicone and a poly (dimethylsiloxane).
 9. The method of claim 1, wherein irradiating comprisesirradiating at least one energy converting material in the polymerizableadhesive composition.
 10. The method of claim 9, wherein said at leastone energy converting material is a downconverting material.
 11. Themethod of claim 10, wherein said downconverting material comprisesinorganic particulates selected from the group consisting of metaloxides; metal sulfides; doped metal oxides; and mixed metalchalcogenides.
 12. The method of claim 10, wherein said downconvertingmaterial comprises at least one member selected from the groupconsisting of Y₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃, LaF₃, LaCl₃,La₂O₃, TiO₂, LuPO₄, YVO₄, YbF₃, YF₃, Na-doped YbF₃, ZnS; ZnSe; MgS; CaS;ZnSeS_(y); ZnSe_(x)S_(y):Cu, Ag, Ce, Tb; alkali lead silicate includingcompositions of SiO₂, B₂O₃, Na₂O, K₂O, PbO, MgO, and Ag, andcombinations, alloys, and layers thereof.
 13. The method of claim 10,wherein the downconverting material comprises a dopant including atleast one member selected from the group consisting of Er, Eu, Yb, Tm,Nd, Mn Tb, Ce, Y, U, Pr, La, Gd and other rare-earth species andcombinations thereof.
 14. The method of claim 9, wherein said at leastone energy converting material further comprises an upconvertingmaterial.
 15. The method of claim 14, wherein said upconverting materialcomprises at least one member selected from the group consisting ofY₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃, LaF₃, LaCl₃, La₂O₃, TiO₂,LuPO₄, YVO₄, YbF₃, YF₃, Na-doped YbF₃, SiO₂ and alloys thereof.
 16. Themethod of claim 1, wherein providing a polymerizable adhesivecomposition comprises: providing a solution containing natural orsynthetic rubber compounds on said surface of the element to be bonded;removing said solvent; polymerizing said rubber compounds.
 17. Themethod of claim 16, wherein the polymerization comprises exposing therubber compounds to at least one member selected from the groupconsisting of x-rays, e-beam, and UV flux.
 18. The method of claim 17,wherein the exposing produces breakage of double bonds in the rubbercompounds followed by bonding of the rubber compounds to the surface ofthe element to be bonded.
 19. A method of adhesive bonding comprising:a) providing a polymerizable adhesive composition on a surface of anelement to be bonded to form an assembly; b) irradiating the assemblywith radiation at a first wavelength capable of vulcanization of bondsin the polymerizable adhesive composition by activation ofsulfur-containing compound with at least one member selected from thegroup consisting of x-ray, e-beam, visible, and infrared light tothereby generate ultraviolet light in the polymerizable adhesivecomposition; and c) adhesively joining two or more components togetherby way of the polymerizable adhesive composition; wherein the surface ofthe element to be bonded comprises at least one member selected from thegroup consisting of a polytetrafluoroethylene, apoly(perfluoroalkylacrylate), a polystyrene, a polyacrylate, apoly(methyl methacrylate), a silicone, a poly(dimethylsiloxane), apolyethylene, a polychlorotrifluoroethylene, a polypropylene, apolyvinyl chloride, a polyvinyl fluoride, a polyvinylidenedichloride, apolyvinylidenedifluoride, a polyacrylamide, a polyethyleneterephthalate, a poly(6-aminocoproicacid), and apoly(11-aminoundecaroicacid).
 20. The method of claim 19, whereinirradiating comprises severing bonds in the adhesive composition topromote said vulcanization.
 21. The method of claim 19, wherein thesulfur-containing compound comprises at least one member selected fromthe group consisting of CaS, ZnSeS, and iron sulfate.
 22. The method ofclaim 19, wherein said polymerizable adhesive composition includes atleast one photoinitiator selected from the group consisting of benzoinethers, benzil ketals, α-dialkoxyacetophenones, α-aminoalkylphenones,acylphosphine oxides, benzophenones/amines, thioxanthones/amines, andtitanocenes.
 23. The method of claim 19, wherein said polymerizableadhesive composition further comprises inorganic particulates selectedfrom the group consisting of: metals and metal alloys, ceramics anddielectrics, and metal-coated polymers.
 24. The method of claim 19,wherein said polymerizable adhesive composition further comprises anorganic component selected from the group consisting of: solvents,viscosity modifiers, surfactants, dispersants, and plasticizers.
 25. Themethod of claim 19, wherein the surface of the element to be bondedcomprises at least one member selected from the group consisting of apolytetrafluoroethylene, a poly(perfluoroalkylacrylate), a polystyrene,a polyacrylate, a poly(methyl methacrylate), a poly(dimethylsiloxane), apolyethylene, a polychlorotrifluoroethylene, a polypropylene, apolyvinyl chloride, a polyvinyl fluoride, a polyvinylidenedichloride, apolyvinylidenedifluoride, a polyacrylamide, a polyethyleneterephthalate, a poly(6-aminocoproicacid), and apoly(11-aminoundecaroicacid).
 26. The method of claim 19, wherein thesurface of the element to be bonded comprises at least one memberselected from the group consisting of a silicone and a poly (dimethylsiloxane).
 27. The method of claim 19, wherein irradiating comprisesirradiating at least one energy converting material in the polymerizableadhesive composition.
 28. The method of claim 27, wherein said at leastone energy converting material is a downconverting material.
 29. Themethod of claim 28, wherein said downconverting material comprisesinorganic particulates selected from the group consisting of metaloxides; metal sulfides; doped metal oxides; and mixed metalchalcogenides.
 30. The method of claim 28, wherein said downconvertingmaterial comprises at least one member selected from the groupconsisting of Y₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃, LaF₃, LaCl₃,La₂O₃, TiO₂, LuPO₄, YVO₄, YbF₃, YF₃, Na-doped YbF₃, ZnS; ZnSe; MgS; CaS;ZnSe_(x)S_(y); ZnSe_(x)S_(y):Cu, Ag, Ce, Tb; and alkali lead silicateincluding compositions of SiO₂, B₂O₃, Na₂O, K₂O, PbO, MgO, Ag, andcombinations, alloys, and layers thereof.
 31. The method of claim 28,wherein the downconverting material comprises a dopant including atleast one member selected from the group consisting of Er, Eu, Yb, Tm,Nd, Mn Tb, Ce, Y, U, Pr, La, Gd and other rare-earth species andcombinations thereof.
 32. The method of claim 27, wherein said at leastone energy converting material further comprises an upconvertingmaterial.
 33. The method of claim 32, wherein said upconverting materialcomprises at least one member selected from the group consisting ofY₂O₃, Y₂O₂S, NaYF₄, NaYbF₄, YAG, YAP, Nd₂O₃, LaF₃, LaCl₃, La₂O₃, TiO₂,LuPO₄, YVO₄, YbF₃, YF₃, Na-doped YbF₃, SiO₂ and alloys thereof.
 34. Themethod of claim 19, wherein said polymerizable adhesive compositionincludes an organic vehicle comprising in part a monomer forming athermoset resin.
 35. The method of claim 34, wherein said thermosetresin is selected from the group consisting of: acrylics, phenolics,urethanes, epoxies, styrenes, and silicones.
 36. The method of claim 19,wherein providing a polymerizable adhesive composition comprises:providing a solution containing natural or synthetic rubber compounds onsaid surface of the element to be bonded; removing said solvent;polymerizing said rubber compounds.
 37. The method of claim 36, whereinthe polymerization comprises exposing the rubber compounds to at leastone member selected from the group consisting of x-rays, e-beam, and UVflux.
 38. The method of claim 37, wherein the exposing produces breakageof double bonds in the rubber compounds followed by bonding of therubber compounds to the surface of the element to be bonded.